For a webservice I use this code to serialize the response:

Dim XmlizedString As [String] = Nothing
Dim memoryStream As New MemoryStream()
Dim xs As New XmlSerializer(p Object.GetType)
Dim xmlTextWriter As New Xml.XmlTextWrit er(memoryStream , System.Text.Enc oding.UTF8)
xs.Serialize(xm lTextWriter, pObject)
memoryStream = DirectCast(xmlT extWriter.BaseS tream, MemoryStream)
Dim r As Byte() = memoryStream.To Array()...