Abstract. Metadata interoperability is an active research area, especially for cultural heritage collections, which consist of heterogeneous objects described by a variety of metadata schemas. In this paper we propose an ontology-based metadata interoperability approach, which exploits, in an optimal way, the semantics of metadata schemas. In particular, we propose the use of CIDOC/CRM ontology as a mediating schema and present a methodology for mapping DC Type Vocabulary to CIDOC/CRM, demonstrating a real-world effort for ontology-based metadata integration.