using System;

using System.IO;

using System.Xml.Serialization;

​

public enum Simple : byte

{

    one = 0x01,

    two = 0x02,

    three = 0x03

}

​

public class Foo

{

    public Simple Simple

    {

        get;

        set;

    }

}

​

public class Program

{

    public static void Main()

    {

        using (StringWriter textWriter = new StringWriter())

        {

            var foo = new Foo{Simple = Simple.three};

            var serializer = new XmlSerializer(foo.GetType());

            serializer.Serialize(textWriter, foo);

            Console.WriteLine(textWriter.ToString());

        }

    }

}