diff --git a/tempest/api/identity/admin/v3/test_credentials.py b/tempest/api/identity/admin/v3/test_credentials.py
index 7c2e8e0..12b236f 100644
--- a/tempest/api/identity/admin/v3/test_credentials.py
+++ b/tempest/api/identity/admin/v3/test_credentials.py
@@ -37,7 +37,7 @@
             cls.projects.append(cls.project['id'])
 
         cls.user_body = cls.users_client.create_user(
-            u_name, description=u_desc, password=u_password,
+            name=u_name, description=u_desc, password=u_password,
             email=u_email, project_id=cls.projects[0])['user']
 
     @classmethod
diff --git a/tempest/api/identity/admin/v3/test_default_project_id.py b/tempest/api/identity/admin/v3/test_default_project_id.py
index a540da7..3616e77 100644
--- a/tempest/api/identity/admin/v3/test_default_project_id.py
+++ b/tempest/api/identity/admin/v3/test_default_project_id.py
@@ -54,7 +54,7 @@
         # default project
         user_name = data_utils.rand_name('user')
         user_body = self.users_client.create_user(
-            user_name,
+            name=user_name,
             password=user_name,
             domain_id=dom_id,
             default_project_id=proj_id)['user']
diff --git a/tempest/api/identity/admin/v3/test_groups.py b/tempest/api/identity/admin/v3/test_groups.py
index 59fcec6..48e5f02 100644
--- a/tempest/api/identity/admin/v3/test_groups.py
+++ b/tempest/api/identity/admin/v3/test_groups.py
@@ -83,7 +83,8 @@
         for i in range(3):
             name = data_utils.rand_name('User')
             password = data_utils.rand_password()
-            user = self.users_client.create_user(name, password)['user']
+            user = self.users_client.create_user(name=name,
+                                                 password=password)['user']
             users.append(user)
             self.addCleanup(self.users_client.delete_user, user['id'])
             self.groups_client.add_group_user(group['id'], user['id'])
@@ -103,7 +104,8 @@
     def test_list_user_groups(self):
         # create a user
         user = self.users_client.create_user(
-            data_utils.rand_name('User'), data_utils.rand_password())['user']
+            name=data_utils.rand_name('User'),
+            password=data_utils.rand_password())['user']
         self.addCleanup(self.users_client.delete_user, user['id'])
         # create two groups, and add user into them
         groups = []
diff --git a/tempest/api/identity/admin/v3/test_inherits.py b/tempest/api/identity/admin/v3/test_inherits.py
index fe20349..0d3d1d6 100644
--- a/tempest/api/identity/admin/v3/test_inherits.py
+++ b/tempest/api/identity/admin/v3/test_inherits.py
@@ -44,7 +44,7 @@
             name=data_utils.rand_name('group-'), project_id=cls.project['id'],
             domain_id=cls.domain['id'])['group']
         cls.user = cls.users_client.create_user(
-            u_name, description=u_desc, password=u_password,
+            name=u_name, description=u_desc, password=u_password,
             email=u_email, project_id=cls.project['id'],
             domain_id=cls.domain['id'])['user']
 
diff --git a/tempest/api/identity/admin/v3/test_list_users.py b/tempest/api/identity/admin/v3/test_list_users.py
index 9691ee8..99df559 100644
--- a/tempest/api/identity/admin/v3/test_list_users.py
+++ b/tempest/api/identity/admin/v3/test_list_users.py
@@ -25,7 +25,7 @@
         # assert the response based on expected and not_expected
         # expected: user expected in the list response
         # not_expected: user, which should not be present in list response
-        body = self.users_client.list_users(params)['users']
+        body = self.users_client.list_users(**params)['users']
         self.assertIn(expected[key], map(lambda x: x[key], body))
         self.assertNotIn(not_expected[key],
                          map(lambda x: x[key], body))
@@ -42,13 +42,13 @@
         cls.users = list()
         u1_name = data_utils.rand_name('test_user')
         cls.domain_enabled_user = cls.users_client.create_user(
-            u1_name, password=alt_password,
+            name=u1_name, password=alt_password,
             email=cls.alt_email, domain_id=cls.domain['id'])['user']
         cls.users.append(cls.domain_enabled_user)
         # Create default not enabled user
         u2_name = data_utils.rand_name('test_user')
         cls.non_domain_enabled_user = cls.users_client.create_user(
-            u2_name, password=alt_password,
+            name=u2_name, password=alt_password,
             email=cls.alt_email, enabled=False)['user']
         cls.users.append(cls.non_domain_enabled_user)
 
diff --git a/tempest/api/identity/admin/v3/test_projects.py b/tempest/api/identity/admin/v3/test_projects.py
index 1879e46..1137191 100644
--- a/tempest/api/identity/admin/v3/test_projects.py
+++ b/tempest/api/identity/admin/v3/test_projects.py
@@ -200,7 +200,7 @@
         u_email = u_name + '@testmail.tm'
         u_password = data_utils.rand_password()
         user = self.users_client.create_user(
-            u_name, description=u_desc, password=u_password,
+            name=u_name, description=u_desc, password=u_password,
             email=u_email, project_id=project['id'])['user']
         # Delete the User at the end of this method
         self.addCleanup(self.users_client.delete_user, user['id'])
diff --git a/tempest/api/identity/admin/v3/test_roles.py b/tempest/api/identity/admin/v3/test_roles.py
index 2b77023..4ecf0a5 100644
--- a/tempest/api/identity/admin/v3/test_roles.py
+++ b/tempest/api/identity/admin/v3/test_roles.py
@@ -44,7 +44,7 @@
             name=data_utils.rand_name('Group'), project_id=cls.project['id'],
             domain_id=cls.domain['id'])['group']
         cls.user_body = cls.users_client.create_user(
-            u_name, description=u_desc, password=cls.u_password,
+            name=u_name, description=u_desc, password=cls.u_password,
             email=u_email, project_id=cls.project['id'],
             domain_id=cls.domain['id'])['user']
         cls.role = cls.roles_client.create_role(
diff --git a/tempest/api/identity/admin/v3/test_tokens.py b/tempest/api/identity/admin/v3/test_tokens.py
index 89cfd5b..fcf4772 100644
--- a/tempest/api/identity/admin/v3/test_tokens.py
+++ b/tempest/api/identity/admin/v3/test_tokens.py
@@ -32,7 +32,7 @@
         u_email = '%s@testmail.tm' % u_name
         u_password = data_utils.rand_password()
         user = self.users_client.create_user(
-            u_name, description=u_desc, password=u_password,
+            name=u_name, description=u_desc, password=u_password,
             email=u_email)['user']
         self.addCleanup(self.users_client.delete_user, user['id'])
         # Perform Authentication
@@ -62,7 +62,7 @@
         # Create a user.
         user_name = data_utils.rand_name(name='user')
         user_password = data_utils.rand_password()
-        user = self.users_client.create_user(user_name,
+        user = self.users_client.create_user(name=user_name,
                                              password=user_password)['user']
         self.addCleanup(self.users_client.delete_user, user['id'])
 
diff --git a/tempest/api/identity/admin/v3/test_trusts.py b/tempest/api/identity/admin/v3/test_trusts.py
index 9c8f1f6..58e2ab8 100644
--- a/tempest/api/identity/admin/v3/test_trusts.py
+++ b/tempest/api/identity/admin/v3/test_trusts.py
@@ -57,7 +57,7 @@
         u_email = self.trustor_username + '@testmail.xx'
         self.trustor_password = data_utils.rand_password()
         user = self.users_client.create_user(
-            self.trustor_username,
+            name=self.trustor_username,
             description=u_desc,
             password=self.trustor_password,
             email=u_email,
diff --git a/tempest/api/identity/admin/v3/test_users.py b/tempest/api/identity/admin/v3/test_users.py
index f200095..1bcec62 100644
--- a/tempest/api/identity/admin/v3/test_users.py
+++ b/tempest/api/identity/admin/v3/test_users.py
@@ -31,7 +31,7 @@
         u_email = u_name + '@testmail.tm'
         u_password = data_utils.rand_password()
         user = self.users_client.create_user(
-            u_name, description=u_desc, password=u_password,
+            name=u_name, description=u_desc, password=u_password,
             email=u_email, enabled=False)['user']
         # Delete the User at the end of this method
         self.addCleanup(self.users_client.delete_user, user['id'])
@@ -71,7 +71,7 @@
         u_name = data_utils.rand_name('user')
         original_password = data_utils.rand_password()
         user = self.users_client.create_user(
-            u_name, password=original_password)['user']
+            name=u_name, password=original_password)['user']
         # Delete the User at the end all test methods
         self.addCleanup(self.users_client.delete_user, user['id'])
         # Update user with new password
@@ -107,7 +107,7 @@
         u_email = u_name + '@testmail.tm'
         u_password = data_utils.rand_password()
         user_body = self.users_client.create_user(
-            u_name, description=u_desc, password=u_password,
+            name=u_name, description=u_desc, password=u_password,
             email=u_email, enabled=False, project_id=u_project['id'])['user']
         # Delete the User at the end of this method
         self.addCleanup(self.users_client.delete_user, user_body['id'])
diff --git a/tempest/api/identity/admin/v3/test_users_negative.py b/tempest/api/identity/admin/v3/test_users_negative.py
index 71e8bc5..5b0fc97 100644
--- a/tempest/api/identity/admin/v3/test_users_negative.py
+++ b/tempest/api/identity/admin/v3/test_users_negative.py
@@ -29,7 +29,7 @@
         u_email = u_name + '@testmail.tm'
         u_password = data_utils.rand_password()
         self.assertRaises(lib_exc.NotFound, self.users_client.create_user,
-                          u_name, u_password,
+                          name=u_name, password=u_password,
                           email=u_email,
                           domain_id=data_utils.rand_uuid_hex())
 
diff --git a/tempest/api/identity/base.py b/tempest/api/identity/base.py
index ce052e6..b512d50 100644
--- a/tempest/api/identity/base.py
+++ b/tempest/api/identity/base.py
@@ -39,7 +39,7 @@
     def get_user_by_name(cls, name, domain_id=None):
         if domain_id:
             params = {'domain_id': domain_id}
-            users = cls.users_client.list_users(params)['users']
+            users = cls.users_client.list_users(**params)['users']
         else:
             users = cls.users_client.list_users()['users']
         user = [u for u in users if u['name'] == name]
@@ -200,7 +200,7 @@
     @classmethod
     def disable_user(cls, user_name, domain_id=None):
         user = cls.get_user_by_name(user_name, domain_id)
-        cls.users_client.update_user(user['id'], user_name, enabled=False)
+        cls.users_client.update_user(user['id'], name=user_name, enabled=False)
 
     @classmethod
     def create_domain(cls):
@@ -221,7 +221,7 @@
         project = self.setup_test_project()
         username = data_utils.rand_name('test_user')
         email = username + '@testmail.tm'
-        user = self._create_test_user(user_name=username, email=email,
+        user = self._create_test_user(name=username, email=email,
                                       project_id=project['id'],
                                       password=password)
         return user
diff --git a/tempest/common/cred_client.py b/tempest/common/cred_client.py
index 2ca9f40..4e3c395 100644
--- a/tempest/common/cred_client.py
+++ b/tempest/common/cred_client.py
@@ -40,8 +40,10 @@
         self.roles_client = roles_client
 
     def create_user(self, username, password, project, email):
-        params = self._create_user_params(username, password,
-                                          project['id'], email)
+        params = {'name': username,
+                  'password': password,
+                  self.project_id_param: project['id'],
+                  'email': email}
         user = self.users_client.create_user(**params)
         if 'user' in user:
             user = user['user']
@@ -94,6 +96,7 @@
 
 
 class V2CredsClient(CredsClient):
+    project_id_param = 'tenantId'
 
     def __init__(self, identity_client, projects_client, users_client,
                  roles_client):
@@ -102,13 +105,6 @@
                                             users_client,
                                             roles_client)
 
-    def _create_user_params(self, username, password, project_id, email):
-        params = {'name': username,
-                  'password': password,
-                  'tenantId': project_id,
-                  'email': email}
-        return params
-
     def create_project(self, name, description):
         tenant = self.projects_client.create_tenant(
             name=name, description=description)['tenant']
@@ -135,6 +131,7 @@
 
 
 class V3CredsClient(CredsClient):
+    project_id_param = 'project_id'
 
     def __init__(self, identity_client, projects_client, users_client,
                  roles_client, domains_client, domain_name):
@@ -152,13 +149,6 @@
             msg = "Requested domain %s could not be found" % domain_name
             raise lib_exc.InvalidCredentials(msg)
 
-    def _create_user_params(self, username, password, project_id, email):
-        params = {'user_name': username,
-                  'password': password,
-                  'project_id': project_id,
-                  'email': email}
-        return params
-
     def create_project(self, name, description):
         project = self.projects_client.create_project(
             name=name, description=description,
diff --git a/tempest/services/identity/v3/json/users_clients.py b/tempest/services/identity/v3/json/users_clients.py
index 73bd343..0dcdacd 100644
--- a/tempest/services/identity/v3/json/users_clients.py
+++ b/tempest/services/identity/v3/json/users_clients.py
@@ -21,56 +21,27 @@
 class UsersClient(rest_client.RestClient):
     api_version = "v3"
 
-    def create_user(self, user_name, password=None, project_id=None,
-                    email=None, domain_id='default', **kwargs):
-        """Creates a user."""
-        en = kwargs.get('enabled', True)
-        description = kwargs.get('description', None)
-        default_project_id = kwargs.get('default_project_id')
-        post_body = {
-            'project_id': project_id,
-            'default_project_id': default_project_id,
-            'description': description,
-            'domain_id': domain_id,
-            'email': email,
-            'enabled': en,
-            'name': user_name,
-            'password': password
-        }
-        post_body = json.dumps({'user': post_body})
+    def create_user(self, **kwargs):
+        """Creates a user.
+
+        Available params: see http://developer.openstack.org/
+                              api-ref/identity/v3/#create-user
+        """
+        post_body = json.dumps({'user': kwargs})
         resp, body = self.post('users', post_body)
         self.expected_success(201, resp.status)
         body = json.loads(body)
         return rest_client.ResponseBody(resp, body)
 
-    def update_user(self, user_id, name, **kwargs):
+    def update_user(self, user_id, **kwargs):
         """Updates a user.
 
         Available params: see http://developer.openstack.org/
                               api-ref-identity-v3.html#updateUser
         """
-        body = self.show_user(user_id)['user']
-        email = kwargs.get('email', body['email'])
-        en = kwargs.get('enabled', body['enabled'])
-        project_id = kwargs.get('project_id', body['project_id'])
-        if 'default_project_id' in body.keys():
-            default_project_id = kwargs.get('default_project_id',
-                                            body['default_project_id'])
-        else:
-            default_project_id = kwargs.get('default_project_id')
-        description = kwargs.get('description', body['description'])
-        domain_id = kwargs.get('domain_id', body['domain_id'])
-        post_body = {
-            'name': name,
-            'email': email,
-            'enabled': en,
-            'project_id': project_id,
-            'default_project_id': default_project_id,
-            'id': user_id,
-            'domain_id': domain_id,
-            'description': description
-        }
-        post_body = json.dumps({'user': post_body})
+        if 'id' not in kwargs:
+            kwargs['id'] = user_id
+        post_body = json.dumps({'user': kwargs})
         resp, body = self.patch('users/%s' % user_id, post_body)
         self.expected_success(200, resp.status)
         body = json.loads(body)
@@ -87,15 +58,26 @@
         self.expected_success(204, resp.status)
         return rest_client.ResponseBody(resp)
 
-    def list_user_projects(self, user_id):
-        """Lists the projects on which a user has roles assigned."""
-        resp, body = self.get('users/%s/projects' % user_id)
+    def list_user_projects(self, user_id, **params):
+        """Lists the projects on which a user has roles assigned.
+
+        Available params: see http://developer.openstack.org/
+                              api-ref/identity/v3/#list-projects-for-user
+        """
+        url = 'users/%s/projects' % user_id
+        if params:
+            url += '?%s' % urllib.urlencode(params)
+        resp, body = self.get(url)
         self.expected_success(200, resp.status)
         body = json.loads(body)
         return rest_client.ResponseBody(resp, body)
 
-    def list_users(self, params=None):
-        """Get the list of users."""
+    def list_users(self, **params):
+        """Get the list of users.
+
+        Available params: see http://developer.openstack.org/
+                              api-ref/identity/v3/#list-users
+        """
         url = 'users'
         if params:
             url += '?%s' % urllib.urlencode(params)
@@ -117,9 +99,16 @@
         self.expected_success(204, resp.status)
         return rest_client.ResponseBody(resp, body)
 
-    def list_user_groups(self, user_id):
-        """Lists groups which a user belongs to."""
-        resp, body = self.get('users/%s/groups' % user_id)
+    def list_user_groups(self, user_id, **params):
+        """Lists groups which a user belongs to.
+
+        Available params: see http://developer.openstack.org/
+            api-ref/identity/v3/#list-groups-to-which-a-user-belongs
+        """
+        url = 'users/%s/groups' % user_id
+        if params:
+            url += '?%s' % urllib.urlencode(params)
+        resp, body = self.get(url)
         self.expected_success(200, resp.status)
         body = json.loads(body)
         return rest_client.ResponseBody(resp, body)