The EU’s higher profile in energy policy matters is arguably due to the increased importance of market liberalisation as a policy objective over the last twenty years. Given the EU’s own competences in the internal market and competition policy, the European Commission has accordingly been able to play a more active role in energy policy-making. Moreover it has been active in extending this approach to its energy relations with its neighbours as manifest in the Energy Charter Treaty, the European Energy Community Treaty and bilateral agreements with third countries. The European Commission has been keen to assert the centrality of market liberalisation to its future energy policy and energy diplomacy, notwithstanding the changes that have taken place in energy markets. Given that there appears to be an increased interest in ‘national champions’ amongst both energy exporting countries and at least some EU member states, how far can the EU sustain a strategy of market liberalisation? The article will place current policy dilemmas (and the EU’s role) in the context of a shifting energy policy agenda – essentially from a supply security ‘economic nationalism’ to market liberalism and back again. It then considers how EU policy is adapting to these circumstances and assesses the effectiveness of this response.