Hi , I have silverlight app that post some data to another web application ,the data to post is converted to base 64 using code byte[] byteArray = Encoding.UTF8.GetBytes(sDataToPost); sDataToPost = Convert.ToBase64String(byteArray); Another webapplication get the data using the code strText = System.Text.Encoding.ASCII.GetString(System.Convert.FromBase64String(postedData)); But it gives the exception invalid length for a base-64 char array Thanks in Advance DNM