AbstractThis paper presents an ontology for systems engineering, by means of a set of information models based on a modelling methodology derived from and a simplification of the ISO 15926 part 2 data model. During the engineering phase of several capital facility projects, the methodology has shown to be much more readable by and helpful in the communication between engineers than the mentioned data model. The ontology represents an interpretation of the Systems Engineering processes as described in ISO 15288 (System Life Cycle Processes) by the author based on years of experience with this standard.Based on the information models and the set of relationships defined herein one can, in combination with a reference data library, specify, build or configure an information system or data exchange mechanism in order to support Systems Engineering processes or set up a specific product knowledge model. Implementation can be done by using a centralized information management system or a distributed one, based on data exchange between involved parties. Both implementations have been validated within pilot projects respectively based on the software tool Relatics and based on a RDF application using triple stores.