In this study the author examines the role of external expert discourse during the policy-shaping stage at the European Commission. In particular, the study explores the EU energy strategies through the lenses of securitization theory. It observes that the concept of the EU energy security has evolved with time depending on particular security discourse. It argues that the external experts have played an important role in this discourse, shaping the EU public officials' understanding and approaches to energy policy. After defining the key conditions of successful securitization, three case studies are presented. Lastly, the study discusses different configurations of factors which led to the successful securitization of energy issues and outlines potential steps for the further research. Key words: energy policy of the European Union, securitization theory, energy security, discourse