The regulation of the sharing of transboundary water resources is a sensitive and politically charged issue of modern international law, since it affects the balance of sovereign national interest and the principle of reasonable and equitable use between coastal states in international law, respectively. Data and information exchange are one of the main criteria for cooperation in the field of intergovernmental management of water resources use. This article discusses the international legal framework for regulating the use of river resources of the Mekong River, as well as the procedures for data and information exchange and sharing as the primary condition for the implementation of cooperation. An analysis of practice and research indicated that although the fundamental, institutional and conceptual foundations are enshrined in various international documents, the de facto practical lack of data causes concern and tense disagreements in the region. Since the adoption of the procedures for data and information exchange and sharing in 2001, data exchange has not been widely used (Hang, Wehn 2016). In conclusion, the author notes that the Mekong River Commission sets a successful example in regulating transboundary water resources as well as in coordinating the relationship between coastal states, donor states, and upstream states. Unfortunately, the data exchange procedure is not yet very effective and the reasons for this are diverse. The author underlines the need to develop specific provisions on operational rules for the provision of data not only from coastal states, but also upstream and donors. Moreover, confidence-building measures need to be developed to create intergovernmental access to reliable data and information. The author pays particular attention to the relationship between non-member states of the Commission - China and Myanmar (up-stream countries) - with member states of the Mekong River Commission. The Memorandum of Understanding and Agreement on providing hydrological data in flood season in 2002 are the main documents that consider the data exchange procedure between the Mekong River Commission and China. The author calls for the development of the same documents for the cooperation of the Commission with Myanmar in order to increase effectively transboundary river cooperation. Methodology The paper was carried out with the use of various scientific methods and approaches, in particular the dialectical method of scientific knowledge as the highest philosophical and worldview research methods. The author accepts general scientific research methods as: analysis, synthesis, analogy, a logical method and a systematic approach, as well as private law methods as a comparative legal and statistical method. © 2021, Springer Nature Switzerland AG.