BPEL4WS is a well-established business process standard that can be used to orchestrate service-based workflows. However, the rapid growth and automation demands of e-business and grid applications require BPEL4WS to provide enhanced semantic annotations to achieve the goal of business processes automation. Here, OWL-S (OWL for Web Services) is designed to represent such kind of semantic information. Furthermore, there exists a similarity in the conceptual model of OWL-S and BPEL4WS that can be employed to overcome the lack of semantics in BPEL4WS by mapping the BPEL4WS process model to the OWL-S suite of ontologies. The mapped OWL-S service can be used to increase flexibility and to automate BPEL based grid scenarios even further. This is achieved by dynamic discovery, composition and invocation of OWL-S services, for example within e-business and grid environments. Hence, the aim of this paper is to establish a mapping from the BPEL process model to the complete OWL-S suite of ontologies. We present a mapping strategy and a tool supporting this strategy. This allows the semantic annotation of workflows defined as BPEL4WS processes to enable the automation of a variety of e-business tasks.