A peer-to-peer (p2p) based service flow management system, SwinDeW-S, could support decentralised Web service composition, deployment and enactment. However, traditional workflow definition languages, such as extended XPDL and service-oriented BPEL4WS, have become insufficient to specify business process semantics, especially the descriptions of inputs, outputs, preconditions and effects. In this paper, we propose a novel solution based on OWL-S, a semantic Web ontology language that leverages service discovery, invocation and negotiation more effectively. The enhanced SwinDeW-S architecture is adapted with advanced ontology-based service profiles, and it takes advantage of a well-developed profile generation tool, which translates the BPEL4WS process models to the OWL-S profiles. As a result, in a new prototype equipped with both BPEL4WS and OWL-S, communications and coordination among service flow peers have become better organised and more efficient.