In recent years, the innovation strategy and development process entitled Product/Service-Systems (PSS), has attracted considerable attention from the research and industrial communities. The many contributions have come from various academic and professional viewpoints, which despite providing a rich view of PSS as a strategy, also leaves some confusion as to what actually constitutes a PSS. The definition of a PSS ontology could provide the basis for a more systematic knowledge gathering within the field and facilitate the application of integrated solutions within the industry. Ontologies provide an effective tool for a knowledge management process, due to their semantic capabilities, interoperability and extendibility. A PSS ontology for domain conceptualisation is proposed that captures the underlying end-user value and relates to existing PSS offerings. The PSS ontology is subsequently integrated into an ontology for the maritime sector, in order to allow for the identification of the PSS implementation opportunities within the industry. A maritime ontology can help the industry to document and reuse tacit knowledge while facilitating the implementation and value assessment of PSS solutions.