I'm not sure that is true of Mono 3.x? Regardless, I also tried with BasicHttpBinding and get a similar (but different) error -- View this message in context: http://mono.1490590.n4.nabble.com/WCF-Mono-server-with-Microsoft-NET-client-tp4661965p4661967.html Sent from the Mono - General mailing list archive at Nabble.com.