Fuel cells, operating with hydrogen or hydrogen-rich fuels, have the potential to become major factors in catalysing the transition to a future sustainable energy system with low CO2 emissions. The importance attached to such developments is rapidly increasing. A large number of countries are now compiling roadmaps, in many cases with specific numerical targets, for the advancement of fuel cell and hydrogen technologies. As just one potent example, the European roadmap for the development and deployment of hydrogen and fuel cell technologies has now set a target of 1 GW of distributed power generation capacity from fuel cells by 2015 and 0.4–1.8 million hydrogen vehicles sold per year by 2020 (European Hydrogen and Fuel Cell Technology Platform, 2005: www.hfpeurope.org/hfp/keydocs)