The Energy Charter Treaty is a multilateral international treaty that contains regulations that, among other things, provide investors of other contracting parties with protection for their investments in the energy sector. Some States, including the Russian Federation, have provisionally applied the Energy Charter Treaty for several years in the wording of Article 45 of the Energy Charter Treaty. This provisional application under Article 45 of the Energy Charter Treaty raised issues that were considered in arbitrational and court proceedings. In this article, the author analyses several Awards on Jurisdiction and Admissibility of Tribunal, namely the Decision on Jurisdiction of Tribunal in the matter of Kardassopoulos v. Georgia and Interim Awards on Jurisdiction and Admissibility of Tribunal in the matter of investors of the former Russian Oil Company Yukos v. Russian Federation. The proceedings for annulment of Awards of the Tribunal in the matter of investors of former Russian Oil Company Yukos v. Russian Federation were brought before courts in the Netherlands, with the proceedings reaching the Supreme Court of the Netherlands, which decided the case on 5 November 2021. On the basis of the aforementioned decisions in the Kardassopoulos v. Georgia and Yukos oil company investors v. the Russian Federation cases, the author of the article focuses on the assessment of the effects of the provisional application of the Energy Charter Treaty, the interpretation of Article 45 of the Energy Charter Treaty, analysing the question of how the provisional application of the Energy Charter Treaty may be limited by the national law of the state that provisionally applies the Energy Charter Treaty.