Abstract:The Distributed Supervision Systems that have been used extensively for the last fifteen years in the process industry are now evolving towards higher level solutions based on better connections between applications and processes that assure that data flows from the process to manage boards. Knowledge sharing seems to be a key issue in integrating these heterogeneous systems. In this paper we present an ontology as a first step to achieving semantic interoperability. The ontology has been conceived within the context of a complex integration problem, in which heterogeneous toolboxes cooperate to deal with several supervision, fault detection and diagnostic tasks for chemical processes. Regarding the current trends in ontology research, our proposal is consistent with top-level ontologies, as these kinds of ontologies seem to overcome the ontology integration problem. We describe a preliminary version of the ontology. The conceptualisation of control variables, system behaviour, supervision tasks, models and system properties is given. All attributes and relationships between each concept has been deployed. The ontology has been developed using Protete2000.