diff --git a/tackerclient/common/constants.py b/tackerclient/common/constants.py
index 7292cb21..7316f092 100644
--- a/tackerclient/common/constants.py
+++ b/tackerclient/common/constants.py
@@ -15,7 +15,7 @@
 
 
 EXT_NS = '_extension_ns'
-XML_NS_V20 = 'http://openstack.org/tacker/api/v1.0'
+XML_NS_V10 = 'http://openstack.org/tacker/api/v1.0'
 XSI_NAMESPACE = "http://www.w3.org/2001/XMLSchema-instance"
 XSI_ATTR = "xsi:nil"
 XSI_NIL_ATTR = "xmlns:xsi"
diff --git a/tackerclient/common/serializer.py b/tackerclient/common/serializer.py
index 798882a5..e10020c1 100644
--- a/tackerclient/common/serializer.py
+++ b/tackerclient/common/serializer.py
@@ -76,7 +76,7 @@ class XMLDictSerializer(DictSerializer):
         if not xmlns:
             xmlns = self.metadata.get('xmlns')
         if not xmlns:
-            xmlns = constants.XML_NS_V20
+            xmlns = constants.XML_NS_V10
         self.xmlns = xmlns
 
     def default(self, data):
@@ -239,7 +239,7 @@ class XMLDeserializer(TextDeserializer):
         self.metadata = metadata or {}
         xmlns = self.metadata.get('xmlns')
         if not xmlns:
-            xmlns = constants.XML_NS_V20
+            xmlns = constants.XML_NS_V10
         self.xmlns = xmlns
 
     def _get_key(self, tag):
diff --git a/tackerclient/v1_0/client.py b/tackerclient/v1_0/client.py
index 6d8e637d..ff0c4a8a 100644
--- a/tackerclient/v1_0/client.py
+++ b/tackerclient/v1_0/client.py
@@ -242,7 +242,7 @@ class ClientBase(object):
         ns = dict([(ext['alias'], ext['namespace']) for ext in exts])
         self.EXTED_PLURALS.update(constants.PLURALS)
         return {'plurals': self.EXTED_PLURALS,
-                'xmlns': constants.XML_NS_V20,
+                'xmlns': constants.XML_NS_V10,
                 constants.EXT_NS: ns}
 
     def content_type(self, _format=None):