The subject matter of this master thesis is the CISG and the energy contracts, or more precisely if and how this convention applies to energy contracts. The CISG is a widely applied all over the world multilateral treaty and it constitutes an example of a successful unification of the private law in the international trade sector as well as a venture which has achieved the reduction of costs from the transactions conducted between the parties. Another important issue of the present thesis is the energy sector and especially the energy contracts. As far as the upstream energy sector is concerned, that is the sector of exploration and production, there are four main types of energy contracts, the concessions, the production-sharing agreements, the joint ventures and the service contracts. The host state contracts are concluded between the state or a national company and a private investor. The internationalization of the host state contracts is in progress because they use to a large extent provisions and clauses that are alike to the ones used in the private sector model contracts so that they can attract foreign investors by assuring them that their investment will be efficient and that it will take place in a safe and stable environment. In addition, there are also the midstream and downstream sectors and the respective energy contracts. Midstream activities include the processing, storage and transportation. In other words, the midstream sector consists the link between the upstream and downstream sector, so the midstream companies, owners and operators of pipelines and storage facilities sign contracts with both the producers and the companies engaged in the downstream sector. Last but not least, the downstream sector includes the refining, the product marketing and the distribution and contracts are signed for the sale of the energy products, like oil and gas with natural or legal persons engaged either in the wholesale or in the retail sector or with the end consumers. Except for the analysis of the energy contracts driven by the aforesaid sectors, an analysis is conducted as regards the commodities, a category of which is also the energy products. The analysis focuses on the meaning of the commodities, the way they function and their markets and it examines the basic legal instruments which can apply to commodity sale contracts, i.e. the CISG, the English law and the Incoterms. The purpose of the present thesis is not only to highlight the importance of the CISG in the International Trade and generally in the transactions field, but also to analyze the how and if the various energy contracts signed can have the CISG as a compass, after of course a review process of the energy contracts and the different categories of them, and all of these topics will be developed under the light of the privotal role Energy possesses today at international level. The following analysis begins from the CISG and its most important provisions, it proceeds with the energy field and particularly the energy contracts and the different types of them and finally it focuses on the law applicable to the energy contracts.