Many models, methods, methodologies and tools exist to help an organization, an enterprise, or more generally a system, to develop interoperability with its partners. However, most of existing works in this domain have been done to develop operational solutions to solve interoperability problems. Basic and fundamental researches, allowing characterizing and measuring the potential of an enterprise to interoperate, are still missing. In particular, this thesis deals with the definition of metrics for evaluating enterprise interoperability. By focusing specifically on interoperability maturity, a Maturity Model for Enterprise Interoperability (MMEI) is elaborated. The proposed MMEI is based on existing relevant maturity models and extends existing works to cover all main aspects and dimensions of enterprise interoperability. Possible contribution from existing scientific theories, in particular General System Theory considered as most relevant, are investigated and core concepts are brought into MMEI. An ontology of enterprise interoperability is also proposed to formalize basic concepts of enterprise interoperability. Based on this ontology, the MMEI has been, thereafter, developed.