The 'hydrogen economy' has the potential to provide a sustainable and secure energy system, and there is a wide and growing literature promoting and exploring different possible hydrogen futures. However, despite broad agreement that hydrogen could make a significant contribution to energy policy goals, the literature exhibits strong disagreements about the form that a future hydrogen economy should take. Visions of the future select, combine and reconfigure individual hydrogen generation, storage, transport and end-use technologies into more or less mutually compatible energy and transportation systems, which embody deeply contested and conflicting views of sustainability. This paper describes the application of a novel foresight methodology, which combined participatory scenario development, using a backcasting approach, with an expert-stakeholder multi-criteria mapping (MCM) process, in order to provide an integrated, transparent assessment of the environmental, social and economic sustainability of six possible future hydrogen energy systems for the UK. The findings suggest that: hydrogen has the potential to deliver substantial sustainability benefits over the status quo, or, business as usual, futures, but that hydrogen is not automatically a sustainable option; carbon emissions are the single most important dimension of sustainability, but that issues other than carbon and cost need to be considered if hydrogen is truly to deliver greater sustainability. Furthermore, there was significant disagreement about which visions were considered more or less sustainable. These findings reflect two important sources of divergence in the final sustainability rankings: uncertainties and contested views of sustainability. (c) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.