Making an investment in energy sector is generally associated with various risks encountered by the foreign energy investors. It is obvious, therefore, that foreign energy investors rely on legal instruments to seek for sufficient protection of their business activities in a host-state. This work analyses provisions of the Energy Charter Treaty aiming at protecting a foreign energy investment, with the reference to several arbitral decisions under the Energy Charter Treaty based investor-state arbitration. Furthermore, discussion is made on provisional application of the Energy Charter Treaty and it is analyzed whether or not a sufficient protection is offered to foreign energy investment in those countries that have not yet ratified the Energy Charter Treaty. This work is recommended for lawyers, investors in energy sector and students with an interest in Energy Law and International Investment Law, or anyone else who may be interested in foreign energy investment.