using System;

    using System.Xml.Serialization;

using System.IO ;

[XmlRoot("test") ] 

public class MyType {

​

​

    [XmlElement("childNode", Namespace="http://flibble")]

    public string Value { get; set; }

} 

​

public class Program

{

    public static void Main()

    {

        MyType mt = new MyType() ;

        mt.Value = "coucou" ;

       XmlSerializerNamespaces ns = new XmlSerializerNamespaces();

        ns.Add("toto", "http://flibble");

        XmlSerializer xser = new XmlSerializer(typeof(MyType));

        MemoryStream ms = new MemoryStream() ;

        xser.Serialize(ms, mt, ns);

ms.Position=0;

        StreamReader sr=new StreamReader(ms);

        Console.WriteLine(sr.ReadToEnd());

    }

}