% in URL String when Decoding

  I am working on a CXML PunchOut system where the Servlet retrieves the 
Shopping Cart data via XML file from the PunchOut site. The Servlet then runs 
the XML file through a URLDecoder. It errors because one ot the product 
descriptions contain a % ( i.e. 50% Polyester).  
   
  First of all, I'm not really sure why the URLDecoder is even being used at 
this point. Is it necessary to decode this URL?  And Second, if it is, is there 
a away to decode the XML file while retaining the % in the description?
   
  I can remove the % from the XML file prior to Decoding it, but would prefer 
to keep the % intact if possible. 
   
  Here is the code:
   
  String cxmlURLDecoded = null;
  String cxmlURLEncoded = request.getParameter("cxml-urlencoded");
   
  // receiving an error: java.lang.IllegalArgumentException
  cxmlURLDecoded = URLDecoder.decode(cxmlURLEncoded);
   
  Thank you,
  Don M.