diff --git modules/rdf/rdf.api.php modules/rdf/rdf.api.php
index e33c5dc..eaf3aca 100644
--- modules/rdf/rdf.api.php
+++ modules/rdf/rdf.api.php
@@ -90,18 +90,13 @@ function hook_rdf_mapping() {
  */
 function hook_rdf_namespaces() {
   return array(
-    'admin'    => 'http://webns.net/mvcb/',
     'content'  => 'http://purl.org/rss/1.0/modules/content/',
     'dc'       => 'http://purl.org/dc/terms/',
     'foaf'     => 'http://xmlns.com/foaf/0.1/',
-    'owl'      => 'http://www.w3.org/2002/07/owl#',
-    'rdf'      => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#',
+    'og'       => 'http://ogp.me/ns#',
     'rdfs'     => 'http://www.w3.org/2000/01/rdf-schema#',
-    'rss'      => 'http://purl.org/rss/1.0/',
-    'tags'     => 'http://www.holygoat.co.uk/owl/redwood/0.1/tags/',
     'sioc'     => 'http://rdfs.org/sioc/ns#',
     'sioct'    => 'http://rdfs.org/sioc/types#',
-    'ctag'     => 'http://commontag.org/ns#',
     'skos'     => 'http://www.w3.org/2004/02/skos/core#',
     'xsd'      => 'http://www.w3.org/2001/XMLSchema#',
   );
diff --git modules/rdf/rdf.module modules/rdf/rdf.module
index d6046cd..98d0236 100644
--- modules/rdf/rdf.module
+++ modules/rdf/rdf.module
@@ -81,10 +81,7 @@ function rdf_rdf_namespaces() {
     'dc'       => 'http://purl.org/dc/terms/',
     'foaf'     => 'http://xmlns.com/foaf/0.1/',
     'og'       => 'http://ogp.me/ns#',
-    'owl'      => 'http://www.w3.org/2002/07/owl#',
-    'rdf'      => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#',
     'rdfs'     => 'http://www.w3.org/2000/01/rdf-schema#',
-    'rss'      => 'http://purl.org/rss/1.0/',
     'sioc'     => 'http://rdfs.org/sioc/ns#',
     'sioct'    => 'http://rdfs.org/sioc/types#',
     'skos'     => 'http://www.w3.org/2004/02/skos/core#',
diff --git modules/rdf/rdf.test modules/rdf/rdf.test
index 159ea69..0bfc0c3 100644
--- modules/rdf/rdf.test
+++ modules/rdf/rdf.test
@@ -688,7 +688,7 @@ class RdfGetRdfNamespacesTestCase extends DrupalWebTestCase {
     // Get all RDF namespaces.
     $ns = rdf_get_namespaces();
 
-    $this->assertEqual($ns['owl'], 'http://www.w3.org/2002/07/owl#', t('A prefix declared once is included.'));
+    $this->assertEqual($ns['rdfs'], 'http://www.w3.org/2000/01/rdf-schema#', t('A prefix declared once is included.'));
     $this->assertEqual($ns['foaf'], 'http://xmlns.com/foaf/0.1/', t('The same prefix declared in several implementations of hook_rdf_namespaces() is valid as long as all the namespaces are the same.'));
     $this->assertEqual($ns['foaf1'], 'http://xmlns.com/foaf/0.1/', t('Two prefixes can be assigned the same namespace.'));
     $this->assertTrue(!isset($ns['dc']), t('A prefix with conflicting namespaces is discarded.'));
diff --git modules/simpletest/tests/common.test modules/simpletest/tests/common.test
index 4529ec1..34c6b74 100644
--- modules/simpletest/tests/common.test
+++ modules/simpletest/tests/common.test
@@ -2017,7 +2017,7 @@ class DrupalGetRdfNamespacesTestCase extends DrupalWebTestCase {
     $xml = new SimpleXMLElement($this->content);
     $ns = $xml->getDocNamespaces();
 
-    $this->assertEqual($ns['owl'], 'http://www.w3.org/2002/07/owl#', t('A prefix declared once is displayed.'));
+    $this->assertEqual($ns['rdfs'], 'http://www.w3.org/2000/01/rdf-schema#', t('A prefix declared once is displayed.'));
     $this->assertEqual($ns['foaf'], 'http://xmlns.com/foaf/0.1/', t('The same prefix declared in several implementations of hook_rdf_namespaces() is valid as long as all the namespaces are the same.'));
     $this->assertEqual($ns['foaf1'], 'http://xmlns.com/foaf/0.1/', t('Two prefixes can be assigned the same namespace.'));
     $this->assertTrue(!isset($ns['dc']), t('A prefix with conflicting namespaces is discarded.'));