Abstract: The article is an attempt based on a generalization of the experience of the European Union (EU), to identify the essential characteristic of supranationality in the context of the interaction of international law with domestic law, to assess the legal nature of the EU and to offer the reader an authorial definition of “supranationality”. The general conclusion of the paper is that supranationality should be understood as an effective form of interstate cooperation and activity within the international organization, based on unity of interests, in which the authority serving these interests receives some degree of autonomy from the participating countries by transferring (conceding) part of their internal powers to it. As a result, its decisions, without prior transformation into domestic law, have a general normative character and direct effect not only on member states, but also on their natural and legal persons, which is ensured by effective enforcement mechanisms. At the same time, the supranational level, which has a considerable number of independent regulatory powers, is hierarchically higher than inter-state level, therefore, its law also has primacy over the national law. Besides, within the framework of the article, particular attention is paid to description of main approaches that characterize the legal essence of the European Union. The author expresses an opinion on the appropriateness of understanding the EU as an international organization of a special kind (sui generis), which combines elements of classical international organizations with supranational features in its functioning.