Before writing your xmlString string you need to clear all response otherwise response string contain html tags and also you need to set content type of response to xml, I suggest this way to get xml from server.
protected void Page_Load(object sender, EventArgs e)
{
Response.Clear();
Response.ContentType = "text/xml";
XmlDocument Xdoc = new XmlDocument();
string xmlString = "<?xml version=\"1.0\"?><company><employee id=\"001\" >John</employee><employee id=\"002\" >Mike</employee></company>";
Xdoc.LoadXml(xmlString);
Xdoc.Save(Response.OutputStream);
Response.End();
}
Example of Retrieve the content of an XML file
http://www.w3schools.com/ajax/tryit.asp?filename=tryajax_xml2[
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