Abstract Securing energy supply for Europe has been for decades at the forefront of the energy policies of individual European Community member countries. However, dealing with energy issues in general and securing energy supply in particular is a new phenomenon within the EU's regulatory framework. One important issue which has not yet been discussed by legal scholars and which has been questioned repeatedly by energy experts, is the question who is actually responsible to guarantee security of energy supply in Europe? Is it the European Community alone? Is it the Member States alone? Or is it both? This question cannot be answered without a detailed legal analysis of the EU law in general, and EU law on division of competences between the Community and the Member States in particular. This article seeks to highlight the complications of this area of law within the EU and expand it to cover the energy sector in order to determine who and under what circumstances is responsible for guaranteeing security of energy supply for the consumers within the EU borders.