Web service composition is currently a very focused-on topic of research, with many studies being proposed by academic and industrial research groups. This paper discusses the design and verification of behavior of composite Web services. We model composite Web services based on two behaviors, namely control and operational. These behaviors communicate through conversation messages. We use state charts to model composite Web services and verify the synchronization of the conversations among them using symbolic model checking with NuSMV. © 2009 The authors and IOS Press.