public static void Main()
var content = @"<?xml version=""1.0"" encoding=""UTF-8""?>
<MyRootElement xmlns=""urn:MyNamespaceUri_1"">
<Description>Red</Description>
<Reference xmlns=""urn:MyNamespaceUri_2"">
XmlDocument doc = new XmlDocument();
var nsmgr = new XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("ns1", "urn:MyNamespaceUri_1");
nsmgr.AddNamespace("ns2", "urn:MyNamespaceUri_2");
XmlNode testNode = doc.SelectSingleNode("/ns1:MyRootElement/Color/ns2:Reference/ID", nsmgr);
Console.WriteLine(testNode.InnerText);