diff --git a/mistral/api/controllers/v2/action.py b/mistral/api/controllers/v2/action.py
index 660189707..32e00eaca 100644
--- a/mistral/api/controllers/v2/action.py
+++ b/mistral/api/controllers/v2/action.py
@@ -1,5 +1,6 @@
 # Copyright 2014 - Mirantis, Inc.
 # Copyright 2015 Huawei Technologies Co., Ltd.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -46,11 +47,12 @@ class ActionsController(rest.RestController, hooks.HookController):
         spec_parser.get_action_list_spec_from_yaml)
 
     @rest_utils.wrap_wsme_controller_exception
-    @wsme_pecan.wsexpose(resources.Action, wtypes.text)
-    def get(self, identifier):
+    @wsme_pecan.wsexpose(resources.Action, wtypes.text, wtypes.text)
+    def get(self, identifier, namespace=''):
         """Return the named action.
 
         :param identifier: ID or name of the Action to get.
+        :param namespace: The namespace of the action.
         """
 
         acl.enforce('actions:get', context.ctx())
@@ -60,17 +62,19 @@ class ActionsController(rest.RestController, hooks.HookController):
         # Use retries to prevent possible failures.
         db_model = rest_utils.rest_retry_on_db_error(
             db_api.get_action_definition
-        )(identifier)
+        )(identifier, namespace=namespace)
 
         return resources.Action.from_db_model(db_model)
 
     @rest_utils.wrap_pecan_controller_exception
     @pecan.expose(content_type="text/plain")
-    def put(self, identifier=None):
+    def put(self, identifier=None, namespace=''):
         """Update one or more actions.
 
         :param identifier: Optional. If provided, it's UUID or name of an
             action. Only one action can be updated with identifier param.
+        :param namespace: Optional. If provided, it's the namespace that
+            the action is under.
 
         NOTE: This text is allowed to have definitions
             of multiple actions. In this case they all will be updated.
@@ -81,6 +85,7 @@ class ActionsController(rest.RestController, hooks.HookController):
 
         LOG.debug("Update action(s) [definition=%s]", definition)
 
+        namespace = namespace or ''
         scope = pecan.request.GET.get('scope', 'private')
         resources.Action.validate_scope(scope)
         if scope == 'public':
@@ -92,7 +97,8 @@ class ActionsController(rest.RestController, hooks.HookController):
                 return actions.update_actions(
                     definition,
                     scope=scope,
-                    identifier=identifier
+                    identifier=identifier,
+                    namespace=namespace
                 )
 
         db_acts = _update_actions()
@@ -105,13 +111,19 @@ class ActionsController(rest.RestController, hooks.HookController):
 
     @rest_utils.wrap_pecan_controller_exception
     @pecan.expose(content_type="text/plain")
-    def post(self):
+    def post(self, namespace=''):
         """Create a new action.
 
+        :param namespace: Optional. The namespace to create the ad-hoc action
+            in. actions with the same name can be added to a given
+            project if they are in two different namespaces.
+            (default namespace is '')
+
         NOTE: This text is allowed to have definitions
             of multiple actions. In this case they all will be created.
         """
         acl.enforce('actions:create', context.ctx())
+        namespace = namespace or ''
 
         definition = pecan.request.text
         scope = pecan.request.GET.get('scope', 'private')
@@ -126,7 +138,9 @@ class ActionsController(rest.RestController, hooks.HookController):
         @rest_utils.rest_retry_on_db_error
         def _create_action_definitions():
             with db_api.transaction():
-                return actions.create_actions(definition, scope=scope)
+                return actions.create_actions(definition,
+                                              scope=scope,
+                                              namespace=namespace)
 
         db_acts = _create_action_definitions()
 
@@ -137,26 +151,27 @@ class ActionsController(rest.RestController, hooks.HookController):
         return resources.Actions(actions=action_list).to_json()
 
     @rest_utils.wrap_wsme_controller_exception
-    @wsme_pecan.wsexpose(None, wtypes.text, status_code=204)
-    def delete(self, identifier):
+    @wsme_pecan.wsexpose(None, wtypes.text, wtypes.text, status_code=204)
+    def delete(self, identifier, namespace=''):
         """Delete the named action.
 
         :param identifier: Name or UUID of the action to delete.
+        :param namespace: The namespace of which the action is in.
         """
         acl.enforce('actions:delete', context.ctx())
-
         LOG.debug("Delete action [identifier=%s]", identifier)
 
         @rest_utils.rest_retry_on_db_error
         def _delete_action_definition():
             with db_api.transaction():
-                db_model = db_api.get_action_definition(identifier)
+                db_model = db_api.get_action_definition(identifier,
+                                                        namespace=namespace)
 
                 if db_model.is_system:
                     msg = "Attempt to delete a system action: %s" % identifier
                     raise exc.DataAccessException(msg)
-
-                db_api.delete_action_definition(identifier)
+                db_api.delete_action_definition(identifier,
+                                                namespace=namespace)
 
         _delete_action_definition()
 
@@ -164,12 +179,13 @@ class ActionsController(rest.RestController, hooks.HookController):
     @wsme_pecan.wsexpose(resources.Actions, types.uuid, int, types.uniquelist,
                          types.list, types.uniquelist, wtypes.text,
                          wtypes.text, resources.SCOPE_TYPES, wtypes.text,
-                         wtypes.text, wtypes.text, wtypes.text, wtypes.text,
-                         wtypes.text)
+                         wtypes.text, wtypes.text, wtypes.text,
+                         wtypes.text, wtypes.text, wtypes.text)
     def get_all(self, marker=None, limit=None, sort_keys='name',
-                sort_dirs='asc', fields='', created_at=None, name=None,
-                scope=None, tags=None, updated_at=None,
-                description=None, definition=None, is_system=None, input=None):
+                sort_dirs='asc', fields='', created_at=None,
+                name=None, scope=None, tags=None,
+                updated_at=None, description=None, definition=None,
+                is_system=None, input=None, namespace=''):
         """Return all actions.
 
         :param marker: Optional. Pagination marker for large data sets.
@@ -199,6 +215,7 @@ class ActionsController(rest.RestController, hooks.HookController):
                            time and date.
         :param updated_at: Optional. Keep only resources with specific latest
                            update time and date.
+        :param namespace: Optional. The namespace of the action.
         """
         acl.enforce('actions:list', context.ctx())
 
@@ -211,7 +228,8 @@ class ActionsController(rest.RestController, hooks.HookController):
             description=description,
             definition=definition,
             is_system=is_system,
-            input=input
+            input=input,
+            namespace=namespace
         )
 
         LOG.debug("Fetch actions. marker=%s, limit=%s, sort_keys=%s, "
diff --git a/mistral/api/controllers/v2/action_execution.py b/mistral/api/controllers/v2/action_execution.py
index 1708be855..33cce07be 100644
--- a/mistral/api/controllers/v2/action_execution.py
+++ b/mistral/api/controllers/v2/action_execution.py
@@ -1,5 +1,6 @@
 # Copyright 2015 - Mirantis, Inc.
 # Copyright 2016 - Brocade Communications Systems, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -144,16 +145,15 @@ class ActionExecutionsController(rest.RestController):
         :param action_ex: Action to execute
         """
         acl.enforce('action_executions:create', context.ctx())
-
         LOG.debug(
             "Create action_execution [action_execution=%s]",
             action_ex
         )
-
         name = action_ex.name
         description = action_ex.description or None
         action_input = action_ex.input or {}
         params = action_ex.params or {}
+        namespace = action_ex.workflow_namespace or ''
 
         if not name:
             raise exc.InputException(
@@ -164,6 +164,7 @@ class ActionExecutionsController(rest.RestController):
             name,
             action_input,
             description=description,
+            namespace=namespace,
             **params
         )
 
diff --git a/mistral/api/controllers/v2/resources.py b/mistral/api/controllers/v2/resources.py
index df6b0ac33..5a24bba36 100644
--- a/mistral/api/controllers/v2/resources.py
+++ b/mistral/api/controllers/v2/resources.py
@@ -1,6 +1,7 @@
 # Copyright 2013 - Mirantis, Inc.
 # Copyright 2018 - Extreme Networks, Inc.
 # Copyright 2019 - NetCracker Technology Corp.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -206,6 +207,7 @@ class Action(resource.Resource, ScopedResource):
 
     created_at = wtypes.text
     updated_at = wtypes.text
+    namespace = wtypes.text
 
     @classmethod
     def sample(cls):
@@ -217,7 +219,8 @@ class Action(resource.Resource, ScopedResource):
             scope='private',
             project_id='a7eb669e9819420ea4bd1453e672c0a7',
             created_at='1970-01-01T00:00:00.000000',
-            updated_at='1970-01-01T00:00:00.000000'
+            updated_at='1970-01-01T00:00:00.000000',
+            namespace=''
         )
 
 
diff --git a/mistral/db/sqlalchemy/migration/alembic_migrations/versions/037_add_namespace_column_to_action_definitions.py b/mistral/db/sqlalchemy/migration/alembic_migrations/versions/037_add_namespace_column_to_action_definitions.py
new file mode 100644
index 000000000..e2e5e2657
--- /dev/null
+++ b/mistral/db/sqlalchemy/migration/alembic_migrations/versions/037_add_namespace_column_to_action_definitions.py
@@ -0,0 +1,67 @@
+# Copyright 2020 Nokia Software.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""add namespace column to action definitions
+
+Revision ID: 037
+Revises: 036
+Create Date: 2020-1-6 10:22:20
+
+"""
+
+# revision identifiers, used by Alembic.
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.engine import reflection
+from sqlalchemy.sql import table, column
+
+revision = '037'
+down_revision = '036'
+
+
+def upgrade():
+    op.add_column(
+        'action_definitions_v2',
+        sa.Column('namespace', sa.String(length=255), nullable=True)
+    )
+
+    inspect = reflection.Inspector.from_engine(op.get_bind())
+
+    unique_constraints = [
+        unique_constraint['name'] for unique_constraint in
+        inspect.get_unique_constraints('action_definitions_v2')
+    ]
+    if 'name' in unique_constraints:
+        op.drop_index('name', table_name='action_definitions_v2')
+
+    if 'action_definitions_v2_name_project_id_key' in unique_constraints:
+        op.drop_constraint('action_definitions_v2_name_project_id_key',
+                           table_name='action_definitions_v2')
+
+    op.create_unique_constraint(
+        None,
+        'action_definitions_v2',
+        ['name', 'namespace', 'project_id']
+    )
+
+    action_def = table('action_definitions_v2', column('namespace'))
+    session = sa.orm.Session(bind=op.get_bind())
+    with session.begin(subtransactions=True):
+        session.execute(
+            action_def.update().values(namespace='').where(
+                action_def.c.namespace is None))  # noqa
+
+    session.commit()
diff --git a/mistral/db/v2/api.py b/mistral/db/v2/api.py
index b77789289..9d8f7d2d5 100644
--- a/mistral/db/v2/api.py
+++ b/mistral/db/v2/api.py
@@ -1,5 +1,6 @@
 # Copyright 2015 - Mirantis, Inc.
 # Copyright 2015 - StackStorm, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -185,22 +186,30 @@ def get_action_definition_by_id(id, fields=()):
     return IMPL.get_action_definition_by_id(id, fields=fields)
 
 
-def get_action_definition(name, fields=()):
-    return IMPL.get_action_definition(name, fields=fields)
+def get_action_definition(name, fields=(), namespace=''):
+    return IMPL.get_action_definition(name, fields=fields, namespace=namespace)
 
 
-def load_action_definition(name, fields=()):
+def load_action_definition(name, fields=(), namespace=''):
     """Unlike get_action_definition this method is allowed to return None."""
+    key = '{}:{}'.format(name, namespace) if namespace else name
     with _ACTION_DEF_CACHE_LOCK:
-        action_def = _ACTION_DEF_CACHE.get(name)
+        action_def = _ACTION_DEF_CACHE.get(key)
 
     if action_def:
         return action_def
 
-    action_def = IMPL.load_action_definition(name, fields=fields)
+    action_def = IMPL.load_action_definition(name, fields=fields,
+                                             namespace=namespace,)
+
+    # If action definition was not found in the workflow namespace,
+    # check in the default namespace
+    if not action_def:
+        action_def = IMPL.load_action_definition(name, fields=fields,
+                                                 namespace='')
 
     with _ACTION_DEF_CACHE_LOCK:
-        _ACTION_DEF_CACHE[name] = (
+        _ACTION_DEF_CACHE[key] = (
             action_def.get_clone() if action_def else None
         )
 
@@ -230,8 +239,8 @@ def create_or_update_action_definition(name, values):
     return IMPL.create_or_update_action_definition(name, values)
 
 
-def delete_action_definition(name):
-    return IMPL.delete_action_definition(name)
+def delete_action_definition(name, namespace=''):
+    return IMPL.delete_action_definition(name, namespace=namespace)
 
 
 def delete_action_definitions(**kwargs):
@@ -539,7 +548,6 @@ def load_environment(name):
 
 def get_environments(limit=None, marker=None, sort_keys=None,
                      sort_dirs=None, **kwargs):
-
     return IMPL.get_environments(
         limit=limit,
         marker=marker,
diff --git a/mistral/db/v2/sqlalchemy/api.py b/mistral/db/v2/sqlalchemy/api.py
index 03aafcf05..09f048791 100644
--- a/mistral/db/v2/sqlalchemy/api.py
+++ b/mistral/db/v2/sqlalchemy/api.py
@@ -1,6 +1,7 @@
 # Copyright 2015 - Mirantis, Inc.
 # Copyright 2015 - StackStorm, Inc.
 # Copyright 2016 - Brocade Communications Systems, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -20,7 +21,6 @@ import re
 import sys
 import threading
 
-
 from oslo_config import cfg
 from oslo_db import exception as db_exc
 from oslo_db import sqlalchemy as oslo_sqlalchemy
@@ -41,11 +41,9 @@ from mistral.services import security
 from mistral.workflow import states
 from mistral_lib import utils
 
-
 CONF = cfg.CONF
 LOG = logging.getLogger(__name__)
 
-
 _SCHEMA_LOCK = threading.RLock()
 _initialized = False
 
@@ -338,7 +336,7 @@ def _get_db_object_by_name_and_namespace_or_id(model, identifier,
 
 
 def _get_db_object_by_name_and_namespace(model, name,
-                                         namespace, insecure=False,
+                                         namespace='', insecure=False,
                                          columns=()):
     query = (
         b.model_query(model, columns=columns)
@@ -654,26 +652,38 @@ def get_action_definition_by_id(id, fields=(), session=None):
 
 
 @b.session_aware()
-def get_action_definition(identifier, fields=(), session=None):
+def get_action_definition(identifier, fields=(), session=None, namespace=''):
     a_def = _get_db_object_by_name_and_namespace_or_id(
         models.ActionDefinition,
         identifier,
+        namespace=namespace,
         columns=fields
     )
+    #  If the action was not found in the given namespace,
+    #  look in the default namespace
+    if not a_def:
+        a_def = _get_db_object_by_name_and_namespace_or_id(
+            models.ActionDefinition,
+            identifier,
+            namespace='',
+            columns=fields
+        )
 
     if not a_def:
         raise exc.DBEntityNotFoundError(
-            "Action definition not found [action_name=%s]" % identifier
+            "Action definition not found [action_name=%s,namespace=%s]"
+            % (identifier, namespace)
         )
 
     return a_def
 
 
 @b.session_aware()
-def load_action_definition(name, fields=(), session=None):
-    return _get_db_object_by_name(
+def load_action_definition(name, fields=(), session=None, namespace=''):
+    return _get_db_object_by_name_and_namespace(
         models.ActionDefinition,
         name,
+        namespace=namespace,
         columns=fields
     )
 
@@ -693,8 +703,8 @@ def create_action_definition(values, session=None):
         a_def.save(session=session)
     except db_exc.DBDuplicateEntry:
         raise exc.DBDuplicateEntryError(
-            "Duplicate entry for Action ['name', 'project_id']:"
-            " {}, {}".format(a_def.name, a_def.project_id)
+            "Duplicate entry for Action ['name', 'namespace', 'project_id']:"
+            " {}, {}, {}".format(a_def.name, a_def.namespace, a_def.project_id)
         )
 
     return a_def
@@ -702,7 +712,8 @@ def create_action_definition(values, session=None):
 
 @b.session_aware()
 def update_action_definition(identifier, values, session=None):
-    a_def = get_action_definition(identifier)
+    namespace = values.get('namespace', '')
+    a_def = get_action_definition(identifier, namespace=namespace)
 
     a_def.update(values.copy())
 
@@ -711,15 +722,19 @@ def update_action_definition(identifier, values, session=None):
 
 @b.session_aware()
 def create_or_update_action_definition(name, values, session=None):
-    if not _get_db_object_by_name(models.ActionDefinition, name):
+    namespace = values.get('namespace', '')
+    if not _get_db_object_by_name_and_namespace(
+            models.ActionDefinition,
+            name,
+            namespace=namespace):
         return create_action_definition(values)
     else:
         return update_action_definition(name, values)
 
 
 @b.session_aware()
-def delete_action_definition(identifier, session=None):
-    a_def = get_action_definition(identifier)
+def delete_action_definition(identifier, namespace='', session=None):
+    a_def = get_action_definition(identifier, namespace=namespace)
 
     session.delete(a_def)
 
@@ -793,8 +808,8 @@ def update_action_execution_heartbeat(id, session=None):
         raise exc.DBEntityNotFoundError
 
     now = utils.utc_now_sec()
-    session.query(models.ActionExecution).\
-        filter(models.ActionExecution.id == id).\
+    session.query(models.ActionExecution). \
+        filter(models.ActionExecution.id == id). \
         update({'last_heartbeat': now})
 
 
@@ -1758,8 +1773,8 @@ def update_resource_member(resource_id, res_type, member_id, values,
 
 @b.session_aware()
 def delete_resource_member(resource_id, res_type, member_id, session=None):
-    query = _secure_query(models.ResourceMember).\
-        filter_by(resource_type=res_type).\
+    query = _secure_query(models.ResourceMember). \
+        filter_by(resource_type=res_type). \
         filter(_get_criterion(resource_id, member_id))
 
     # TODO(kong): Check association with cron triggers when deleting a workflow
diff --git a/mistral/db/v2/sqlalchemy/models.py b/mistral/db/v2/sqlalchemy/models.py
index ce410afdc..834020738 100644
--- a/mistral/db/v2/sqlalchemy/models.py
+++ b/mistral/db/v2/sqlalchemy/models.py
@@ -1,5 +1,6 @@
 # Copyright 2015 - Mirantis, Inc.
 # Copyright 2015 - StackStorm, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -31,7 +32,6 @@ from mistral import exceptions as exc
 from mistral.services import security
 from mistral_lib import utils
 
-
 # Definition objects.
 
 CONF = cfg.CONF
@@ -174,9 +174,12 @@ class ActionDefinition(Definition):
     """Contains info about registered Actions."""
 
     __tablename__ = 'action_definitions_v2'
-
+    namespace = sa.Column(sa.String(255), nullable=True)
     __table_args__ = (
-        sa.UniqueConstraint('name', 'project_id'),
+        sa.UniqueConstraint(
+            'name',
+            'namespace',
+            'project_id'),
         sa.Index('%s_is_system' % __tablename__, 'is_system'),
         sa.Index('%s_action_class' % __tablename__, 'action_class'),
         sa.Index('%s_project_id' % __tablename__, 'project_id'),
@@ -346,7 +349,6 @@ for cls in utils.iter_subclasses(Execution):
         retval=True
     )
 
-
 # Many-to-one for 'ActionExecution' and 'TaskExecution'.
 
 ActionExecution.task_execution_id = sa.Column(
@@ -405,7 +407,6 @@ WorkflowExecution.root_execution = relationship(
     lazy='select'
 )
 
-
 # Many-to-one for 'TaskExecution' and 'WorkflowExecution'.
 
 TaskExecution.workflow_execution_id = sa.Column(
diff --git a/mistral/engine/action_handler.py b/mistral/engine/action_handler.py
index 4fa526b92..fd364d84d 100644
--- a/mistral/engine/action_handler.py
+++ b/mistral/engine/action_handler.py
@@ -1,5 +1,6 @@
 # Copyright 2015 - Mirantis, Inc.
 # Copyright 2016 - Brocade Communications Systems, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -22,7 +23,6 @@ from mistral.engine import actions
 from mistral.engine import task_handler
 from mistral import exceptions as exc
 
-
 LOG = logging.getLogger(__name__)
 
 
@@ -31,7 +31,6 @@ def on_action_complete(action_ex, result):
     task_ex = action_ex.task_execution
 
     action = _build_action(action_ex)
-
     try:
         action.complete(result)
     except exc.MistralException as e:
@@ -87,8 +86,10 @@ def _build_action(action_ex):
     adhoc_action_name = action_ex.runtime_context.get('adhoc_action_name')
 
     if adhoc_action_name:
-        action_def = actions.resolve_action_definition(adhoc_action_name)
-
+        action_def = actions.resolve_action_definition(
+            adhoc_action_name,
+            namespace=action_ex.workflow_namespace
+        )
         return actions.AdHocAction(action_def, action_ex=action_ex)
 
     action_def = actions.resolve_action_definition(action_ex.name)
@@ -96,9 +97,9 @@ def _build_action(action_ex):
     return actions.PythonAction(action_def, action_ex=action_ex)
 
 
-def build_action_by_name(action_name):
-    action_def = actions.resolve_action_definition(action_name)
-
+def build_action_by_name(action_name, namespace=''):
+    action_def = actions.resolve_action_definition(action_name,
+                                                   namespace=namespace)
     action_cls = (actions.PythonAction if not action_def.spec
                   else actions.AdHocAction)
 
diff --git a/mistral/engine/actions.py b/mistral/engine/actions.py
index 39f01d880..aeb963762 100644
--- a/mistral/engine/actions.py
+++ b/mistral/engine/actions.py
@@ -37,7 +37,6 @@ from mistral.workflow import states
 from mistral_lib import actions as ml_actions
 from mistral_lib import utils
 
-
 LOG = logging.getLogger(__name__)
 CONF = cfg.CONF
 
@@ -152,7 +151,8 @@ class Action(object):
         return True
 
     def _create_action_execution(self, input_dict, runtime_ctx, is_sync,
-                                 desc='', action_ex_id=None):
+                                 desc='', action_ex_id=None, namespace=''):
+
         action_ex_id = action_ex_id or utils.generate_unicode_uuid()
 
         values = {
@@ -162,6 +162,7 @@ class Action(object):
             'state': states.RUNNING,
             'input': input_dict,
             'runtime_context': runtime_ctx,
+            'workflow_namespace': namespace,
             'description': desc,
             'is_sync': is_sync
         }
@@ -245,7 +246,6 @@ class PythonAction(Action):
         # to be updated with the action execution ID after the action execution
         # DB object is created.
         action_ex_id = utils.generate_unicode_uuid()
-
         self._create_action_execution(
             self._prepare_input(input_dict),
             self._prepare_runtime_context(index, safe_rerun),
@@ -253,7 +253,6 @@ class PythonAction(Action):
             desc=desc,
             action_ex_id=action_ex_id
         )
-
         execution_context = self._prepare_execution_context()
 
         # Register an asynchronous command to send the action to
@@ -320,7 +319,8 @@ class PythonAction(Action):
         try:
             prepared_input_dict = self._prepare_input(input_dict)
 
-            a = a_m.get_action_class(self.action_def.name)(
+            a = a_m.get_action_class(self.action_def.name,
+                                     self.action_def.namespace)(
                 **prepared_input_dict
             )
 
@@ -356,9 +356,9 @@ class PythonAction(Action):
 
         if self.action_ex:
             exc_ctx['action_execution_id'] = self.action_ex.id
-            exc_ctx['callback_url'] = (
-                '/v2/action_executions/%s' % self.action_ex.id
-            )
+            exc_ctx['callback_url'] = ('/v2/action_executions/%s'
+                                       % self.action_ex.id
+                                       )
 
         return exc_ctx
 
@@ -394,7 +394,8 @@ class AdHocAction(PythonAction):
         self.action_spec = spec_parser.get_action_spec(action_def.spec)
 
         base_action_def = db_api.load_action_definition(
-            self.action_spec.get_base()
+            self.action_spec.get_base(),
+            namespace=action_def.namespace
         )
 
         if not base_action_def:
@@ -539,10 +540,12 @@ class AdHocAction(PythonAction):
 
             base_name = base.spec['base']
             try:
-                base = db_api.get_action_definition(base_name)
+                base = db_api.get_action_definition(base_name,
+                                                    namespace=base.namespace)
             except exc.DBEntityNotFoundError:
                 raise exc.InvalidActionException(
-                    "Failed to find action [action_name=%s]" % base_name
+                    "Failed to find action [action_name=%s namespace=%s] "
+                    % (base_name, base.namespace)
                 )
 
         # if the action is repeated
@@ -554,6 +557,13 @@ class AdHocAction(PythonAction):
 
         return base
 
+    def _create_action_execution(self, input_dict, runtime_ctx, is_sync,
+                                 desc='', action_ex_id=None):
+        super()._create_action_execution(input_dict,
+                                         runtime_ctx, is_sync,
+                                         desc, action_ex_id,
+                                         self.adhoc_action_def.namespace)
+
 
 class WorkflowAction(Action):
     """Workflow action."""
@@ -650,12 +660,13 @@ class WorkflowAction(Action):
 
 
 def resolve_action_definition(action_spec_name, wf_name=None,
-                              wf_spec_name=None):
+                              wf_spec_name=None, namespace=''):
     """Resolve action definition accounting for ad-hoc action namespacing.
 
     :param action_spec_name: Action name according to a spec.
     :param wf_name: Workflow name.
     :param wf_spec_name: Workflow name according to a spec.
+    :param namespace: The namespace of the action.
     :return: Action definition (python or ad-hoc).
     """
 
@@ -671,14 +682,17 @@ def resolve_action_definition(action_spec_name, wf_name=None,
 
         action_full_name = "%s.%s" % (wb_name, action_spec_name)
 
-        action_db = db_api.load_action_definition(action_full_name)
+        action_db = db_api.load_action_definition(action_full_name,
+                                                  namespace=namespace)
 
     if not action_db:
-        action_db = db_api.load_action_definition(action_spec_name)
+        action_db = db_api.load_action_definition(action_spec_name,
+                                                  namespace=namespace)
 
     if not action_db:
         raise exc.InvalidActionException(
-            "Failed to find action [action_name=%s]" % action_spec_name
+            "Failed to find action [action_name=%s] in [namespace=%s]" %
+            (action_spec_name, namespace)
         )
 
     return action_db
diff --git a/mistral/engine/base.py b/mistral/engine/base.py
index 9130d20dc..f0686be79 100644
--- a/mistral/engine/base.py
+++ b/mistral/engine/base.py
@@ -1,5 +1,6 @@
 # Copyright 2014 - Mirantis, Inc.
 # Copyright 2017 - Brocade Communications Systems, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -48,12 +49,13 @@ class Engine(object):
 
     @abc.abstractmethod
     def start_action(self, action_name, action_input,
-                     description=None, **params):
+                     description=None, namespace='', **params):
         """Starts the specific action.
 
         :param action_name: Action name.
         :param action_input: Action input data as a dictionary.
         :param description: Execution description.
+        :param namespace: The namespace of the action.
         :param params: Additional options for action running.
         :return: Action execution object.
         """
diff --git a/mistral/engine/default_engine.py b/mistral/engine/default_engine.py
index 951f95051..8b1da720d 100644
--- a/mistral/engine/default_engine.py
+++ b/mistral/engine/default_engine.py
@@ -2,6 +2,7 @@
 # Copyright 2015 - StackStorm, Inc.
 # Copyright 2016 - Brocade Communications Systems, Inc.
 # Copyright 2018 - Extreme Networks, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -83,9 +84,10 @@ class DefaultEngine(base.Engine):
     @db_utils.retry_on_db_error
     @post_tx_queue.run
     def start_action(self, action_name, action_input,
-                     description=None, **params):
+                     description=None, namespace='', **params):
         with db_api.transaction():
-            action = action_handler.build_action_by_name(action_name)
+            action = action_handler.build_action_by_name(action_name,
+                                                         namespace=namespace)
 
             action.validate_input(action_input)
 
@@ -102,7 +104,6 @@ class DefaultEngine(base.Engine):
 
             if not sync and (save or not is_action_sync):
                 action.schedule(action_input, target, timeout=timeout)
-
                 return action.action_ex.get_clone()
 
             output = action.run(
@@ -111,7 +112,6 @@ class DefaultEngine(base.Engine):
                 save=False,
                 timeout=timeout
             )
-
             state = states.SUCCESS if output.is_success() else states.ERROR
 
             if not save:
@@ -122,9 +122,9 @@ class DefaultEngine(base.Engine):
                     description=description,
                     input=action_input,
                     output=output.to_dict(),
-                    state=state
+                    state=state,
+                    workflow_namespace=namespace
                 )
-
             action_ex_id = u.generate_unicode_uuid()
 
             values = {
@@ -134,7 +134,8 @@ class DefaultEngine(base.Engine):
                 'input': action_input,
                 'output': output.to_dict(),
                 'state': state,
-                'is_sync': is_action_sync
+                'is_sync': is_action_sync,
+                'workflow_namespace': namespace
             }
 
             return db_api.create_action_execution(values)
@@ -147,7 +148,6 @@ class DefaultEngine(base.Engine):
         with db_api.transaction():
             if wf_action:
                 action_ex = db_api.get_workflow_execution(action_ex_id)
-
                 # If result is None it means that it's a normal subworkflow
                 # output and we just need to fetch it from the model.
                 # This is just an optimization to not send data over RPC
@@ -170,7 +170,6 @@ class DefaultEngine(base.Engine):
                 action_ex = db_api.get_workflow_execution(action_ex_id)
             else:
                 action_ex = db_api.get_action_execution(action_ex_id)
-
             action_handler.on_action_update(action_ex, state)
 
             return action_ex.get_clone()
diff --git a/mistral/engine/engine_server.py b/mistral/engine/engine_server.py
index 5e7472e91..2be3390a7 100644
--- a/mistral/engine/engine_server.py
+++ b/mistral/engine/engine_server.py
@@ -157,22 +157,24 @@ class EngineServer(service_base.MistralService):
         )
 
     def start_action(self, rpc_ctx, action_name,
-                     action_input, description, params):
+                     action_input, description, namespace, params):
         """Receives calls over RPC to start actions on engine.
 
         :param rpc_ctx: RPC request context.
         :param action_name: name of the Action.
         :param action_input: input dictionary for Action.
         :param description: description of new Action execution.
+        :param namespace: The namespace of the action.
         :param params: extra parameters to run Action.
         :return: Action execution.
         """
         LOG.info(
             "Received RPC request 'start_action'[name=%s, input=%s, "
-            "description=%s, params=%s]",
+            "description=%s, namespace=%s params=%s]",
             action_name,
             utils.cut(action_input),
             description,
+            namespace,
             params
         )
 
@@ -180,6 +182,7 @@ class EngineServer(service_base.MistralService):
             action_name,
             action_input,
             description,
+            namespace=namespace,
             **params
         )
 
@@ -198,7 +201,6 @@ class EngineServer(service_base.MistralService):
             action_ex_id,
             result.cut_repr() if result else '<unknown>'
         )
-
         return self.engine.on_action_complete(action_ex_id, result, wf_action)
 
     def on_action_update(self, rpc_ctx, action_ex_id, state, wf_action):
diff --git a/mistral/engine/tasks.py b/mistral/engine/tasks.py
index 518c7abec..2f89955c1 100644
--- a/mistral/engine/tasks.py
+++ b/mistral/engine/tasks.py
@@ -691,7 +691,8 @@ class RegularTask(Task):
         action_def = actions.resolve_action_definition(
             action_name,
             self.wf_ex.name,
-            self.wf_spec.get_name()
+            self.wf_spec.get_name(),
+            namespace=self.wf_ex.workflow_namespace
         )
 
         if action_def.spec:
diff --git a/mistral/executors/default_executor.py b/mistral/executors/default_executor.py
index 2aa06f04b..7813c1d6c 100644
--- a/mistral/executors/default_executor.py
+++ b/mistral/executors/default_executor.py
@@ -88,7 +88,6 @@ class DefaultExecutor(base.Executor):
                 return None
 
             return error_result
-
         if redelivered and not safe_rerun:
             msg = (
                 "Request to run action %s was redelivered, but action %s "
diff --git a/mistral/rpc/clients.py b/mistral/rpc/clients.py
index c9674e2f1..345bf8d0c 100644
--- a/mistral/rpc/clients.py
+++ b/mistral/rpc/clients.py
@@ -2,6 +2,7 @@
 # Copyright 2015 - StackStorm, Inc.
 # Copyright 2017 - Brocade Communications Systems, Inc.
 # Copyright 2018 - Extreme Networks, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -150,12 +151,13 @@ class EngineClient(eng.Engine):
 
     @base.wrap_messaging_exception
     def start_action(self, action_name, action_input,
-                     description=None, **params):
+                     description=None, namespace='', **params):
         """Starts action sending a request to engine over RPC.
 
         :param action_name: Action name.
         :param action_input: Action input data as a dictionary.
         :param description: Execution description.
+        :param namespace: The namespace of the action.
         :param params: Additional options for action running.
         :return: Action execution.
         """
@@ -165,6 +167,7 @@ class EngineClient(eng.Engine):
             action_name=action_name,
             action_input=action_input or {},
             description=description,
+            namespace=namespace,
             params=params
         )
 
@@ -372,7 +375,6 @@ class ExecutorClient(exe.Executor):
             action will be interrupted
         :return: Action result.
         """
-
         rpc_kwargs = {
             'action_ex_id': action_ex_id,
             'action_cls_str': action_cls_str,
diff --git a/mistral/services/action_manager.py b/mistral/services/action_manager.py
index 35c8d62e9..b8b99bd6f 100644
--- a/mistral/services/action_manager.py
+++ b/mistral/services/action_manager.py
@@ -1,5 +1,6 @@
 # Copyright 2014 - Mirantis, Inc.
 # Copyright 2014 - StackStorm, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -51,7 +52,7 @@ def get_registered_actions(**kwargs):
 
 
 def register_action_class(name, action_class_str, attributes,
-                          description=None, input_str=None):
+                          description=None, input_str=None, namespace=''):
     values = {
         'name': name,
         'action_class': action_class_str,
@@ -59,7 +60,8 @@ def register_action_class(name, action_class_str, attributes,
         'description': description,
         'input': input_str,
         'is_system': True,
-        'scope': 'public'
+        'scope': 'public',
+        'namespace': namespace
     }
 
     try:
@@ -81,7 +83,7 @@ def sync_db():
         register_standard_actions()
 
 
-def _register_dynamic_action_classes():
+def _register_dynamic_action_classes(namespace=''):
     for generator in generator_factory.all_generators():
         actions = generator.create_actions()
 
@@ -98,11 +100,12 @@ def _register_dynamic_action_classes():
                 action_class_str,
                 attrs,
                 action['description'],
-                action['arg_list']
+                action['arg_list'],
+                namespace=namespace
             )
 
 
-def register_action_classes():
+def register_action_classes(namespace=''):
     mgr = extension.ExtensionManager(
         namespace='mistral.actions',
         invoke_on_load=False
@@ -120,23 +123,24 @@ def register_action_classes():
             action_class_str,
             attrs,
             description=description,
-            input_str=input_str
+            input_str=input_str,
+            namespace=namespace
         )
 
-    _register_dynamic_action_classes()
+    _register_dynamic_action_classes(namespace=namespace)
 
 
-def get_action_db(action_name):
-    return db_api.load_action_definition(action_name)
+def get_action_db(action_name, namespace=''):
+    return db_api.load_action_definition(action_name, namespace=namespace)
 
 
-def get_action_class(action_full_name):
+def get_action_class(action_full_name, namespace=''):
     """Finds action class by full action name (i.e. 'namespace.action_name').
 
     :param action_full_name: Full action name (that includes namespace).
     :return: Action class or None if not found.
     """
-    action_db = get_action_db(action_full_name)
+    action_db = get_action_db(action_full_name, namespace)
 
     if action_db:
         return action_factory.construct_action_class(
diff --git a/mistral/services/actions.py b/mistral/services/actions.py
index 118f1bb31..7d4492abe 100644
--- a/mistral/services/actions.py
+++ b/mistral/services/actions.py
@@ -1,4 +1,5 @@
 # Copyright 2015 - Mirantis, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -19,18 +20,22 @@ from mistral import exceptions as exc
 from mistral.lang import parser as spec_parser
 
 
-def create_actions(definition, scope='private'):
+def create_actions(definition, scope='private', namespace=''):
     action_list_spec = spec_parser.get_action_list_spec_from_yaml(definition)
 
     db_actions = []
 
     for action_spec in action_list_spec.get_actions():
-        db_actions.append(create_action(action_spec, definition, scope))
+        db_actions.append(create_action(
+            action_spec,
+            definition,
+            scope,
+            namespace))
 
     return db_actions
 
 
-def update_actions(definition, scope='private', identifier=None):
+def update_actions(definition, scope='private', identifier=None, namespace=''):
     action_list_spec = spec_parser.get_action_list_spec_from_yaml(definition)
     actions = action_list_spec.get_actions()
 
@@ -48,32 +53,35 @@ def update_actions(definition, scope='private', identifier=None):
             action_spec,
             definition,
             scope,
-            identifier=identifier
+            identifier=identifier,
+            namespace=namespace
+
         ))
 
     return db_actions
 
 
-def create_or_update_actions(definition, scope='private'):
+def create_or_update_actions(definition, scope='private', namespace=''):
     action_list_spec = spec_parser.get_action_list_spec_from_yaml(definition)
 
     db_actions = []
 
     for action_spec in action_list_spec.get_actions():
         db_actions.append(
-            create_or_update_action(action_spec, definition, scope)
+            create_or_update_action(action_spec, definition, scope, namespace)
         )
 
     return db_actions
 
 
-def create_action(action_spec, definition, scope):
+def create_action(action_spec, definition, scope, namespace):
     return db_api.create_action_definition(
-        _get_action_values(action_spec, definition, scope)
+        _get_action_values(action_spec, definition, scope, namespace)
     )
 
 
-def update_action(action_spec, definition, scope, identifier=None):
+def update_action(action_spec, definition, scope, identifier=None,
+                  namespace=''):
     action = db_api.load_action_definition(action_spec.get_name())
 
     if action and action.is_system:
@@ -82,7 +90,7 @@ def update_action(action_spec, definition, scope, identifier=None):
             action.name
         )
 
-    values = _get_action_values(action_spec, definition, scope)
+    values = _get_action_values(action_spec, definition, scope, namespace)
 
     return db_api.update_action_definition(
         identifier if identifier else values['name'],
@@ -90,7 +98,7 @@ def update_action(action_spec, definition, scope, identifier=None):
     )
 
 
-def create_or_update_action(action_spec, definition, scope):
+def create_or_update_action(action_spec, definition, scope, namespace):
     action = db_api.load_action_definition(action_spec.get_name())
 
     if action and action.is_system:
@@ -99,7 +107,7 @@ def create_or_update_action(action_spec, definition, scope):
             action.name
         )
 
-    values = _get_action_values(action_spec, definition, scope)
+    values = _get_action_values(action_spec, definition, scope, namespace)
 
     return db_api.create_or_update_action_definition(values['name'], values)
 
@@ -117,7 +125,7 @@ def get_input_list(action_input):
     return input_list
 
 
-def _get_action_values(action_spec, definition, scope):
+def _get_action_values(action_spec, definition, scope, namespace=''):
     action_input = action_spec.to_dict().get('input', [])
     input_list = get_input_list(action_input)
 
@@ -129,7 +137,8 @@ def _get_action_values(action_spec, definition, scope):
         'spec': action_spec.to_dict(),
         'is_system': False,
         'input': ", ".join(input_list) if input_list else None,
-        'scope': scope
+        'scope': scope,
+        'namespace': namespace
     }
 
     return values
diff --git a/mistral/services/workbooks.py b/mistral/services/workbooks.py
index 34b7ba904..df93750eb 100644
--- a/mistral/services/workbooks.py
+++ b/mistral/services/workbooks.py
@@ -1,4 +1,5 @@
 # Copyright 2015 - Mirantis, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -57,9 +58,9 @@ def update_workbook_v2(definition, namespace='', scope='private',
     return wb_db
 
 
-def _on_workbook_update(wb_db, wb_spec, namespace):
-    # TODO(hardikj) Handle actions for namespace
-    db_actions = _create_or_update_actions(wb_db, wb_spec.get_actions())
+def _on_workbook_update(wb_db, wb_spec, namespace=''):
+    db_actions = _create_or_update_actions(wb_db, wb_spec.get_actions(),
+                                           namespace=namespace)
     db_wfs = _create_or_update_workflows(
         wb_db,
         wb_spec.get_workflows(),
@@ -69,7 +70,7 @@ def _on_workbook_update(wb_db, wb_spec, namespace):
     return db_actions, db_wfs
 
 
-def _create_or_update_actions(wb_db, actions_spec):
+def _create_or_update_actions(wb_db, actions_spec, namespace):
     db_actions = []
 
     if actions_spec:
@@ -88,7 +89,8 @@ def _create_or_update_actions(wb_db, actions_spec):
                 'is_system': False,
                 'input': ', '.join(input_list) if input_list else None,
                 'scope': wb_db.scope,
-                'project_id': wb_db.project_id
+                'project_id': wb_db.project_id,
+                'namespace': namespace
             }
 
             db_actions.append(
diff --git a/mistral/tests/unit/api/v2/test_action_executions.py b/mistral/tests/unit/api/v2/test_action_executions.py
index 2dad135b8..8a729e5f5 100644
--- a/mistral/tests/unit/api/v2/test_action_executions.py
+++ b/mistral/tests/unit/api/v2/test_action_executions.py
@@ -304,7 +304,8 @@ class TestActionExecutionsController(base.APITest):
             json.loads(action_exec['input']),
             description=None,
             save_result=True,
-            run_sync=True
+            run_sync=True,
+            namespace=''
         )
 
     @mock.patch.object(rpc_clients.EngineClient, 'start_action')
@@ -331,7 +332,8 @@ class TestActionExecutionsController(base.APITest):
             action_exec['name'],
             json.loads(action_exec['input']),
             description=None,
-            timeout=2
+            timeout=2,
+            namespace=''
         )
 
     @mock.patch.object(rpc_clients.EngineClient, 'start_action')
@@ -358,7 +360,8 @@ class TestActionExecutionsController(base.APITest):
             action_exec['name'],
             json.loads(action_exec['input']),
             description=None,
-            save_result=True
+            save_result=True,
+            namespace=''
         )
 
     @mock.patch.object(rpc_clients.EngineClient, 'start_action')
@@ -374,7 +377,9 @@ class TestActionExecutionsController(base.APITest):
         self.assertEqual(201, resp.status_int)
         self.assertEqual('{"result": "123"}', resp.json['output'])
 
-        f.assert_called_once_with('nova.servers_list', {}, description=None)
+        f.assert_called_once_with('nova.servers_list', {},
+                                  description=None,
+                                  namespace='')
 
     def test_post_bad_result(self):
         resp = self.app.post_json(
diff --git a/mistral/tests/unit/db/v2/test_sqlalchemy_db_api.py b/mistral/tests/unit/db/v2/test_sqlalchemy_db_api.py
index 50f60c33b..c9df95047 100644
--- a/mistral/tests/unit/db/v2/test_sqlalchemy_db_api.py
+++ b/mistral/tests/unit/db/v2/test_sqlalchemy_db_api.py
@@ -1,5 +1,6 @@
 # Copyright 2015 - Mirantis, Inc.
 # Copyright 2015 - StackStorm, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -1085,7 +1086,8 @@ ACTION_DEFINITIONS = [
         'action_class': 'mypackage.my_module.Action1',
         'attributes': None,
         'project_id': '<default-project>',
-        'created_at': datetime.datetime(2016, 12, 1, 15, 0, 0)
+        'created_at': datetime.datetime(2016, 12, 1, 15, 0, 0),
+        'namespace': ''
     },
     {
         'name': 'action2',
@@ -1094,7 +1096,8 @@ ACTION_DEFINITIONS = [
         'action_class': 'mypackage.my_module.Action2',
         'attributes': None,
         'project_id': '<default-project>',
-        'created_at': datetime.datetime(2016, 12, 1, 15, 1, 0)
+        'created_at': datetime.datetime(2016, 12, 1, 15, 1, 0),
+        'namespace': ''
     },
     {
         'name': 'action3',
@@ -1104,7 +1107,8 @@ ACTION_DEFINITIONS = [
         'action_class': 'mypackage.my_module.Action3',
         'attributes': None,
         'project_id': '<default-project>',
-        'created_at': datetime.datetime(2016, 12, 1, 15, 2, 0)
+        'created_at': datetime.datetime(2016, 12, 1, 15, 2, 0),
+        'namespace': ''
     },
 ]
 
@@ -1154,8 +1158,8 @@ class ActionDefinitionTest(SQLAlchemyTest):
 
         self.assertRaisesWithMessage(
             exc.DBDuplicateEntryError,
-            "Duplicate entry for Action ['name', 'project_id']: action1"
-            ", <default-project>",
+            "Duplicate entry for Action ['name', 'namespace', 'project_id']:"
+            " action1, , <default-project>",
             db_api.create_action_definition,
             ACTION_DEFINITIONS[0]
         )
diff --git a/mistral/tests/unit/engine/test_action_caching.py b/mistral/tests/unit/engine/test_action_caching.py
index 86c639f6b..8a1374b04 100644
--- a/mistral/tests/unit/engine/test_action_caching.py
+++ b/mistral/tests/unit/engine/test_action_caching.py
@@ -28,9 +28,7 @@ cfg.CONF.set_default('auth_enable', False, group='pecan')
 
 
 class LookupUtilsTest(base.EngineTestCase):
-
-    def test_action_definition_cache_ttl(self):
-        action = """---
+    ACTION = """---
         version: '2.0'
 
         action1:
@@ -39,7 +37,7 @@ class LookupUtilsTest(base.EngineTestCase):
             result: $
         """
 
-        wf_text = """---
+    WF_TEXT = """---
         version: '2.0'
 
         wf:
@@ -61,16 +59,23 @@ class LookupUtilsTest(base.EngineTestCase):
               pause-before: true
         """
 
-        wf_service.create_workflows(wf_text)
+    def test_action_definition_cache_ttl(self):
+        namespace = 'test_namespace'
+        wf_service.create_workflows(self.WF_TEXT, namespace=namespace)
 
         # Create an action.
-        db_actions = action_service.create_actions(action)
+        db_actions = action_service.create_actions(self.ACTION,
+                                                   namespace=namespace)
 
         self.assertEqual(1, len(db_actions))
-        self._assert_single_item(db_actions, name='action1')
+        self._assert_single_item(db_actions,
+                                 name='action1',
+                                 namespace=namespace)
 
         # Explicitly mark the action to be deleted after the test execution.
-        self.addCleanup(db_api.delete_action_definitions, name='action1')
+        self.addCleanup(db_api.delete_action_definitions,
+                        name='action1',
+                        namespace=namespace)
 
         # Reinitialise the cache with reduced action_definition_cache_time
         # to make sure the test environment is under control.
@@ -84,13 +89,15 @@ class LookupUtilsTest(base.EngineTestCase):
         self.addCleanup(cache_patch.stop)
 
         # Start workflow.
-        wf_ex = self.engine.start_workflow('wf')
+        wf_ex = self.engine.start_workflow('wf', wf_namespace=namespace)
 
         self.await_workflow_paused(wf_ex.id)
 
         # Check that 'action1' 'echo' and 'noop' are cached.
-        self.assertEqual(3, len(db_api._ACTION_DEF_CACHE))
-        self.assertIn('action1', db_api._ACTION_DEF_CACHE)
+        self.assertEqual(5, len(db_api._ACTION_DEF_CACHE))
+        self.assertIn('action1:test_namespace', db_api._ACTION_DEF_CACHE)
+        self.assertIn('std.noop:test_namespace', db_api._ACTION_DEF_CACHE)
+        self.assertIn('std.echo:test_namespace', db_api._ACTION_DEF_CACHE)
         self.assertIn('std.noop', db_api._ACTION_DEF_CACHE)
         self.assertIn('std.echo', db_api._ACTION_DEF_CACHE)
 
@@ -110,6 +117,7 @@ class LookupUtilsTest(base.EngineTestCase):
         self.await_workflow_success(wf_ex.id)
 
         # Check all actions are cached again.
-        self.assertEqual(2, len(db_api._ACTION_DEF_CACHE))
-        self.assertIn('action1', db_api._ACTION_DEF_CACHE)
+        self.assertEqual(3, len(db_api._ACTION_DEF_CACHE))
+        self.assertIn('action1:test_namespace', db_api._ACTION_DEF_CACHE)
         self.assertIn('std.echo', db_api._ACTION_DEF_CACHE)
+        self.assertIn('std.echo:test_namespace', db_api._ACTION_DEF_CACHE)
diff --git a/mistral/tests/unit/engine/test_adhoc_actions.py b/mistral/tests/unit/engine/test_adhoc_actions.py
index c962bc812..b497151a1 100644
--- a/mistral/tests/unit/engine/test_adhoc_actions.py
+++ b/mistral/tests/unit/engine/test_adhoc_actions.py
@@ -1,4 +1,5 @@
 # Copyright 2014 - Mirantis, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -15,6 +16,7 @@
 from oslo_config import cfg
 
 from mistral.db.v2 import api as db_api
+from mistral import exceptions as exc
 from mistral.services import workbooks as wb_service
 from mistral.tests.unit.engine import base
 from mistral.workflow import states
@@ -24,7 +26,6 @@ from mistral.workflow import states
 # the change in value is not permanent.
 cfg.CONF.set_default('auth_enable', False, group='pecan')
 
-
 WORKBOOK = """
 ---
 version: '2.0'
@@ -305,6 +306,78 @@ class AdhocActionsTest(base.EngineTestCase):
 
         self.await_workflow_running(wf_ex.id)
 
+    def test_adhoc_action_difinition_with_namespace(self):
+        namespace = 'ad-hoc_test'
+        namespace2 = 'ad-hoc_test2'
+        wb_text = """---
+
+        version: '2.0'
+
+        name: my_wb_namespace
+
+        actions:
+          test_env:
+            base: std.echo
+            base-input:
+              output: '{{ env().foo }}'
+
+        workflows:
+          wf_namespace:
+            type: direct
+            input:
+              - str1
+            output:
+                workflow_result: '{{ _.printenv_result }}'
+
+            tasks:
+              printenv:
+                action: test_env
+                publish:
+                  printenv_result: '{{ task().result }}'
+        """
+
+        wb_service.create_workbook_v2(wb_text, namespace=namespace)
+        wb_service.create_workbook_v2(wb_text, namespace=namespace2)
+
+        with db_api.transaction():
+            action_def = db_api.get_action_definitions(
+                name='my_wb_namespace.test_env', )
+
+            self.assertEqual(2, len(action_def))
+
+            action_def = db_api.get_action_definitions(
+                name='my_wb_namespace.test_env',
+                namespace=namespace)
+
+            self.assertEqual(1, len(action_def))
+
+            self.assertRaises(exc.DBEntityNotFoundError,
+                              db_api.get_action_definition,
+                              name='my_wb_namespace.test_env')
+
+    def test_adhoc_action_execution_with_namespace(self):
+        namespace = 'ad-hoc_test'
+
+        wb_service.create_workbook_v2(WORKBOOK, namespace=namespace)
+        wf_ex = self.engine.start_workflow(
+            'my_wb.wf4',
+            wf_input={'str1': 'a'},
+            env={'foo': 'bar'},
+            wf_namespace=namespace
+        )
+
+        self.await_workflow_success(wf_ex.id)
+
+        with db_api.transaction():
+            action_execs = db_api.get_action_executions(
+                name='std.echo',
+                workflow_namespace=namespace)
+            self.assertEqual(1, len(action_execs))
+            context = action_execs[0].runtime_context
+            self.assertEqual('my_wb.test_env',
+                             context.get('adhoc_action_name'))
+            self.assertEqual(namespace, action_execs[0].workflow_namespace)
+
     def test_adhoc_action_runtime_context_name(self):
         wf_ex = self.engine.start_workflow(
             'my_wb.wf4',
diff --git a/mistral/tests/unit/engine/test_run_action.py b/mistral/tests/unit/engine/test_run_action.py
index 2ee7d3209..a16d19e6d 100644
--- a/mistral/tests/unit/engine/test_run_action.py
+++ b/mistral/tests/unit/engine/test_run_action.py
@@ -1,4 +1,5 @@
 # Copyright 2015 - Mirantis, Inc.
+# Copyright 2020 Nokia Software.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -100,6 +101,81 @@ class RunActionEngineTest(base.EngineTestCase):
         self.assertEqual('Hello!', action_ex.output['result'])
         self.assertEqual(states.SUCCESS, action_ex.state)
 
+    def test_run_action_with_namespace(self):
+        namespace = 'test_namespace'
+        action = """---
+        version: '2.0'
+
+        concat_namespace:
+          base: std.echo
+          base-input:
+            output: <% $.left %><% $.right %>
+          input:
+            - left
+            - right
+
+        concat_namespace2:
+          base: concat_namespace
+          base-input:
+            left: <% $.left %><% $.center %>
+            right: <% $.right %>
+          input:
+            - left
+            - center
+            - right
+        """
+        actions.create_actions(action, namespace=namespace)
+
+        self.assertRaises(exc.InvalidActionException,
+                          self.engine.start_action,
+                          'concat_namespace',
+                          {'left': 'Hello, ', 'right': 'John Doe!'},
+                          save_result=True,
+                          namespace='')
+
+        action_ex = self.engine.start_action(
+            'concat_namespace',
+            {'left': 'Hello, ', 'right': 'John Doe!'},
+            save_result=True,
+            namespace=namespace
+        )
+
+        self.assertEqual(namespace, action_ex.workflow_namespace)
+
+        self.await_action_success(action_ex.id)
+
+        with db_api.transaction():
+            action_ex = db_api.get_action_execution(action_ex.id)
+            self.assertEqual(states.SUCCESS, action_ex.state)
+            self.assertEqual({'result': u'Hello, John Doe!'}, action_ex.output)
+
+        action_ex = self.engine.start_action(
+            'concat_namespace2',
+            {'left': 'Hello, ', 'center': 'John', 'right': ' Doe!'},
+            save_result=True,
+            namespace=namespace
+        )
+        self.assertEqual(namespace, action_ex.workflow_namespace)
+        self.await_action_success(action_ex.id)
+
+        with db_api.transaction():
+            action_ex = db_api.get_action_execution(action_ex.id)
+            self.assertEqual(states.SUCCESS, action_ex.state)
+            self.assertEqual('Hello, John Doe!', action_ex.output['result'])
+
+    def test_run_action_with_invalid_namespace(self):
+        # This test checks the case in which, the action with that name is
+        # not found with the given name, if an action was found with the
+        # same name in default namespace, that action will run.
+
+        action_ex = self.engine.start_action(
+            'concat',
+            {'left': 'Hello, ', 'right': 'John Doe!'},
+            save_result=True,
+            namespace='namespace'
+        )
+        self.assertIsNotNone(action_ex)
+
     @mock.patch.object(
         std_actions.EchoAction,
         'run',
@@ -325,7 +401,7 @@ class RunActionEngineTest(base.EngineTestCase):
         self.engine.start_action('fake_action', {'input': 'Hello'})
 
         self.assertEqual(1, def_mock.call_count)
-        def_mock.assert_called_with('fake_action')
+        def_mock.assert_called_with('fake_action', namespace='')
 
         self.assertEqual(0, validate_mock.call_count)
 
diff --git a/mistral/tests/unit/services/test_action_service.py b/mistral/tests/unit/services/test_action_service.py
index c7c8e289b..3b0a90000 100644
--- a/mistral/tests/unit/services/test_action_service.py
+++ b/mistral/tests/unit/services/test_action_service.py
@@ -1,4 +1,5 @@
 # Copyright 2014 - Mirantis, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -15,17 +16,16 @@
 from oslo_config import cfg
 
 from mistral.db.v2 import api as db_api
+from mistral.exceptions import DBEntityNotFoundError
 from mistral.lang import parser as spec_parser
 from mistral.services import actions as action_service
 from mistral.tests.unit import base
 from mistral_lib import utils
 
-
 # Use the set_default method to set value otherwise in certain test cases
 # the change in value is not permanent.
 cfg.CONF.set_default('auth_enable', False, group='pecan')
 
-
 ACTION_LIST = """
 ---
 version: '2.0'
@@ -54,6 +54,8 @@ action1:
     result: $
 """
 
+NAMESPACE = 'test_namespace'
+
 
 class ActionServiceTest(base.DbTestCase):
     def setUp(self):
@@ -78,14 +80,35 @@ class ActionServiceTest(base.DbTestCase):
 
         # Action 2.
         action2_db = self._assert_single_item(db_actions, name='action2')
+        self.assertEqual('', action2_db.namespace)
         action2_spec = spec_parser.get_action_spec(action2_db.spec)
 
         self.assertEqual('action2', action2_spec.get_name())
         self.assertEqual('std.echo', action1_spec.get_base())
         self.assertDictEqual({'output': 'Hey'}, action2_spec.get_base_input())
 
+    def test_create_actions_in_namespace(self):
+        db_actions = action_service.create_actions(ACTION_LIST,
+                                                   namespace=NAMESPACE)
+
+        self.assertEqual(2, len(db_actions))
+
+        action1_db = self._assert_single_item(db_actions, name='action1')
+        self.assertEqual(NAMESPACE, action1_db.namespace)
+
+        action2_db = self._assert_single_item(db_actions, name='action2')
+        self.assertEqual(NAMESPACE, action2_db.namespace)
+
+        self.assertRaises(
+            DBEntityNotFoundError,
+            db_api.get_action_definition,
+            name='action1',
+            namespace=''
+        )
+
     def test_update_actions(self):
-        db_actions = action_service.create_actions(ACTION_LIST)
+        db_actions = action_service.create_actions(ACTION_LIST,
+                                                   namespace=NAMESPACE)
 
         self.assertEqual(2, len(db_actions))
 
@@ -97,7 +120,8 @@ class ActionServiceTest(base.DbTestCase):
         self.assertDictEqual({'output': 'Hi'}, action1_spec.get_base_input())
         self.assertDictEqual({}, action1_spec.get_input())
 
-        db_actions = action_service.update_actions(UPDATED_ACTION_LIST)
+        db_actions = action_service.update_actions(UPDATED_ACTION_LIST,
+                                                   namespace=NAMESPACE)
 
         # Action 1.
         action1_db = self._assert_single_item(db_actions, name='action1')
@@ -112,3 +136,29 @@ class ActionServiceTest(base.DbTestCase):
             action1_spec.get_input().get('param1'),
             utils.NotDefined
         )
+
+        self.assertRaises(
+            DBEntityNotFoundError,
+            action_service.update_actions,
+            UPDATED_ACTION_LIST,
+            namespace=''
+        )
+
+    def test_delete_action(self):
+
+        # Create action.
+        action_service.create_actions(ACTION_LIST, namespace=NAMESPACE)
+
+        action = db_api.get_action_definition('action1', namespace=NAMESPACE)
+        self.assertEqual(NAMESPACE, action.get('namespace'))
+        self.assertEqual('action1', action.get('name'))
+
+        # Delete action.
+        db_api.delete_action_definition('action1', namespace=NAMESPACE)
+
+        self.assertRaises(
+            DBEntityNotFoundError,
+            db_api.get_action_definition,
+            name='action1',
+            namespace=NAMESPACE
+        )
diff --git a/mistral/tests/unit/services/test_workbook_service.py b/mistral/tests/unit/services/test_workbook_service.py
index 25abce86c..24fa56c76 100644
--- a/mistral/tests/unit/services/test_workbook_service.py
+++ b/mistral/tests/unit/services/test_workbook_service.py
@@ -1,4 +1,5 @@
 # Copyright 2014 - Mirantis, Inc.
+# Copyright 2020 Nokia Software.
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -181,7 +182,10 @@ class WorkbookServiceTest(base.DbTestCase):
         self.assertIsNotNone(wb_db.spec)
         self.assertListEqual(['test'], wb_db.tags)
 
-        db_actions = db_api.get_action_definitions(name='my_wb.concat')
+        db_actions = db_api.get_action_definitions(
+            name='my_wb.concat',
+            namespace=namespace
+        )
 
         self.assertEqual(1, len(db_actions))
 
@@ -279,7 +283,8 @@ class WorkbookServiceTest(base.DbTestCase):
         wb_service.create_workbook_v2(WORKBOOK, namespace=namespace)
 
         db_wfs = db_api.get_workflow_definitions()
-        db_actions = db_api.get_action_definitions(name='my_wb.concat')
+        db_actions = db_api.get_action_definitions(name='my_wb.concat',
+                                                   namespace=namespace)
 
         self.assertEqual(2, len(db_wfs))
         self.assertEqual(1, len(db_actions))
@@ -287,8 +292,8 @@ class WorkbookServiceTest(base.DbTestCase):
         db_api.delete_workbook('my_wb', namespace=namespace)
 
         db_wfs = db_api.get_workflow_definitions()
-        db_actions = db_api.get_action_definitions(name='my_wb.concat')
-
+        db_actions = db_api.get_action_definitions(name='my_wb.concat',
+                                                   namespace=namespace)
         # Deleting workbook shouldn't delete workflows and actions
         self.assertEqual(2, len(db_wfs))
         self.assertEqual(1, len(db_actions))
diff --git a/releasenotes/notes/namespace_for_adhoc_actions.yaml b/releasenotes/notes/namespace_for_adhoc_actions.yaml
new file mode 100644
index 000000000..d190b0df3
--- /dev/null
+++ b/releasenotes/notes/namespace_for_adhoc_actions.yaml
@@ -0,0 +1,14 @@
+---
+features:
+  - |
+    Add support for creating ad-hoc actions in a namespace. Creating actions
+    with same name is now possible inside the same project now. This feature
+    is backward compatible.
+
+    All existing actions are assumed to be in the default namespace,
+    represented by an empty string. Also, if an action is created without a
+    namespace specified, it is assumed to be in the default namespace.
+
+    If an ad-hoc action is created inside a workbook, then the namespace of the workbook
+    would be also it's namespace.
+