The purpose of the article is to identify the status of complex institutional entity, consisting of a commercial company “Inmarsat” and intergovernmental organization - the International organization of mobile satellite communications, in contemporary international law. The complex of general scientific and special methods (analysis and synthesis, historical method, system approach) was used in the research of the problem. As a result, it is established that the basis of relations in complex institutional entity is regulated by an international treaty. Further, the provisions of the international treaty are specified in the resolutions of international organizations relating to the subject of cooperation. The agreement on public communication services should be referred to as a private law contract, since it is signed by an intergovernmental organization and a non-state entity - the service provider.