The responseText property is read-only and represents the response entity body as a string. The XMLHTTP object tries to decode the response into a unicode string, assuming a default encoding of UTF-8. However, it can decode any type of UCS-2 (big or little endian) or UTC-4 encoding as long as the server sends the appropriate unicode byte order mark. It does not process the XML '<?' coding declaration. If you know the response is going to be XML, you should use the responseXML property instead.