The debate-taking place at present about a future European energy system focuses on hydrogen as a potential future energy carrier. Hydrogen corridors offer, among other things, the possibilities of coping with the energy resource limitations for hydrogen production in the EU25 and improving energy supply security. This study deals with the assessment of economically optimal hydrogen corridors between the EU25 and neighbouring countries using consistent hydrogen scenarios, cost and potential calculations, the identification of barriers and policy recommendations. The analysis shows that specific hydrogen corridors (e.g. Norway, Iceland) could play a role for supplying renewable hydrogen in or shortly after the introduction phase of hydrogen as an energy carrier in the EU. Subsequently, with an increasing demand for hydrogen in the EU25, other large-scale hydrogen corridors based on renewables constitute a very promising option from both the economic perspective as well as from the perspective of realizing a sustainable hydrogen supply. However, competing utilisation possibilities for renewable resources and the potentially increasing demand for hydrogen within the neighbouring countries themselves may limit this option. Hydrogen corridors based on fossil or nuclear feedstock are not promising because it is usually more beneficial to transport the feedstock or electricity itself instead of hydrogen. (C) 2006 Elsevier Ltd. All rights reserved.