A characteristic trend in the development of international law in the second half of the XX century and early XXI century is thesignificant expansion of the law-making function of international intergovernmental organizations, which are obtaining an increasinglyimportant role each year in resolving common issues in the political, economic, social, educational and other spheres, acting on behalfand in the interests of the states that formed them. In the system of international organizations of economic nature, an important placebelongs to the Organization for Economic Cooperation and Development, which unites 36 industrialized countries as at 2020. Duringalmost 70 years of the OECD existence, the organization has developed and adopted a wide variety of legal instruments aimed ataddressing the widest range of issues related to various sectors of the economy, the fight against corruption, education and science, theenvironment, etc., recommendations, declarations, international agreements, ad hoc instruments. Based on a purely quantitative indicator,legally binding international treaties have a relatively small percentage of the entire normative body of acts adopted under theOECD. In total, 13 conventions were adopted within its framework, 10 of which are in force today. However, the conventions, deve -loped under the aegis of the OECD, are quite successful examples of codification and progressive development of international law inthe fields of: anti-corruption (Convention to Combat Bribery of Foreign Officials in International Business Transactions of December17, 1997); administrative assistance in the field of taxation (Convention on Mutual Administrative Assistance in Tax Matters of January25, 1988 and Protocol amending the Convention on Mutual Administrative Assistance in Tax Matters of May 27, 2010); counteractionto the tax base erosion and profit shift (Multilateral Convention to Implement Tax Treaty Related Measures to Prevent Base Erosionand Profit Shifting of November 24, 2016); nuclear safety, liability for damage caused by nuclear incidents (Convention on theEstablishment of a Security Control in the Field of Nuclear Energy of December 20, 1957, Convention on Third Party Liability in theField of Nuclear Energy of July 29, 1960 (Paris Convention, 1960), Convention of 31 January 1963 Supplementary to the Paris Conventionof July 29, 1960 (Brussels Supplementary Convention).