Today, model-driven development is getting more sophisticated and can be used for modeling enterprises and developing application systems. Since current interoperability solutions operate essentially at a syntactical level, technologies have to be developed enabling interoperability based on middleware, and development platforms have to be enriched with machine-understandable semantics. Our approach of ‘Ontology-based Model Transformation’ will contribute to these challenges by lifting syntactical metamodel description into ontologies and by a formalism for ontology-based model transformations.