During the last decades eGovernment has been a vivid, dynamic research and development area. As services are being transformed, electronic documents and web services appear every day in many countries, the involved stakeholders are in urgent need for an instrument to structure governmental administration processes, service composition and provision - in a way that eGovernment transformation can be constantly managed. This paper presents the creation of an eGovernment ontology, and the development of a knowledgebased registry of governmental services in Greece. This Registry is an advanced web portal, devoted to the formal description, composition and publishing of traditional, electronic and web services, including the relevant electronic documents, information systems and as well the process descriptions and the work-flow models in an integrated knowledge base. Through such a repository, the discovery of services by users or systems has been automated, resulting in an important tool f...