Semantic Web Services (SWSs) aim to improve the possibilities for automated discovery, composition and invocation of Web Services by providing ontology-based service descriptions expressed in a formal language. Several approaches have been driving the development of Semantic Web Service frameworks such as OWL-S (Ontology Web Language for Services), WSMO (Web Service Modeling Ontology) and WSDL-S (Semantic Annotation of Web Service Description Language descriptions). This paper focuses on WSMO; it aims to give a service ontology specification according to WSMO and using the reverse engineering techniques.