Nowadays the Semantic Web is a leading web technology, which enables semantic interoperability between structurally and semantically heterogeneous web sources and web users. Ontologies are a key of semantic interoperability and the main vehicle of the development of the Semantic Web. One of the most challenging and important tasks of ontology engineering is integration of ontologies because with the purpose to built a common ontology for all web sources and consumers in a domain. The present paper describes an approach of assessing data quality of ontology matching that allows evaluating correctness of mapping concepts and relationships from one ontological fragment to another. The purpose of correct mapping is to find identical and synonymous concepts and relationships in ontologies facilitating their integration to a common ontology, which serves as a base for attaining interoperability.