>>Not sure what you mean. Where are you 'sending' it ? Anything to do with HTML ?
>
>This is a Web Service responding to a client. The client is, for now, a simple VB.NET desktop application.
>
>This is a regular .NET ASMX Web Service returning a XML string.
>
>As part of the XML structure, some datasets are inserted (converted into XML, with the dataset structure), and in there, I may have all kind of characters.

I wonder if something like this might work:

Dim s1 As String = theDataset.GetXml()

Dim bytes As Byte() = Encoding.[Default].GetBytes(s1)
Dim UTF8String As String = Encoding.UTF8.GetString(bytes)
Dim dec As String = New XmlDocument().CreateXmlDeclaration("1.0", "UTF-8", Nothing).OuterXml
Dim XMLoutput As String = dec & UTF8String