Several factors have led to growing interest in a hydrogen energy economy, especially for transportation. A successful transition to a major role for hydrogen will require much greater cost-effectiveness, fueling infrastructure, consumer acceptance, and a strategy for its basis in renewable energy feedstocks. Despite modest attention to the need for a sustainable hydrogen energy system in several countries, in most cases in the short to mid term hydrogen will be produced from fossil fuels. This paper surveys the global status of hydrogen energy research and development (R&D) and public policy, along with the likely energy mix for making it. The current state of hydrogen energy R&D among auto, energy and fuel-cell companies is also briefly reviewed. Just two major auto companies and two nations have specific targets and timetables for hydrogen fuel cells or vehicle production, although the EU also has an aggressive, less specific strategy. Iceland and Brazil are the only nations where renewable energy feedstocks are envisioned as the major or sole future source of hydrogen. None of these plans, however, are very certain. Thus, serious questions about the sustainability of a hydrogen economy can be raised. (c) 2004 Elsevier Ltd. All rights reserved.