The area of legal regulation related to customs norm formation isn’t clearly designated and sufficientlyexamined in the doctrine of international law. Also, there is no unified point of view on its title. A varietyof terms can be met in scientific studies. The author proposes to entitle this area of international lawas “law of international customs” — the most accurate term, corresponding to its content. The articlereveals the role and place of the law of international customs in the international legal system. The differencesand similarities of this institute of international law in relation to the law of treaties are shown.Scientific doctrines on the content and development of this institute of international law are also considered.The author shows which rules are lying on the basis of customs norm-formation and substantiateshis position on this issue. The object and the subject of regulation of the law of international customsare clarified. The question of norm-formation and its stages is examined. The article reveals influenceof treaty rules, decisions of judicial and other international bodies on the process of custom normformation.Questions over necessity of the codification of this process, development of appropriatecriteria relating to the formation of international custom and its norms are risen. The author proposesto develop relevant draft articles, adopting them as a UN resolution, and then to sign a Convention onthe Law of international customs, which should fix currently established customary rules of internationallaw, and also new treaty rules aimed to streamline the custom norm-formation, giving it more rigorous,systematic view. The state of scientific researches in this area and the ways of their further developmentare shown. Separate formulations of the law of international customs are presented. The authorgives definition of the law of international customs, which is proposed to be understood as the instituteof international law, including a set of customary rules of international law regulating interstate relationsin the questions of international custom establishment, its validity, amending and termination of existence,the conceptual apparatus in this area.