diff --git a/examples/sos.html b/examples/sos.html
index 7020261aaa..d3b6266510 100644
--- a/examples/sos.html
+++ b/examples/sos.html
@@ -127,7 +127,7 @@
                     var offering = this.SOSCapabilities.contents.offeringList[name];
                     var xml = this.obsformat.write({
                         eventTime: 'latest',
-                        resultModel: 'measurement',
+                        resultModel: 'om:Measurement',
                         responseMode: 'inline',
                         procedure: feature.attributes.id,
                         offering: name,
diff --git a/lib/OpenLayers/Format/SOSGetObservation.js b/lib/OpenLayers/Format/SOSGetObservation.js
index eac5bf5702..c6823cc8cd 100644
--- a/lib/OpenLayers/Format/SOSGetObservation.js
+++ b/lib/OpenLayers/Format/SOSGetObservation.js
@@ -104,6 +104,7 @@ OpenLayers.Format.SOSGetObservation = OpenLayers.Class(OpenLayers.Format.XML, {
      */
     write: function(options) {
         var node = this.writeNode("sos:GetObservation", options);
+        node.setAttribute("xmlns:om", this.namespaces.om);
         this.setAttributeNS(
             node, this.namespaces.xsi,
             "xsi:schemaLocation", this.schemaLocation