It is difficult to conceive of additional praises for this book beyond the many superlative accounts and recommendations printed on the cover. Indeed, Hoffmann (editor, The Hydrogen and Fuel Cell Letter) has written a persuasively clear, technically accurate, and convincingly optimistic book on the future of hydrogen in this revised edition (1st ed., CH, Jan'02, 39-2815). Any well-read energy expert can attest to its exhaustive research and painstaking detail--a technologist's delight. Hoffmann discusses all proven and promising end uses of hydrogen in the energy economy, from transportation to residential cooking and heating, giving detailed technical, economic, and environmental comparisons with competing energy sources and conversion systems. He goes beyond the energy arena to discuss nonenergy uses of hydrogen, an area that is rarely as well presented in popular hydrogen economy literature. This reviewer gives Hoffmann special accolades for his references to C. Marchetti, L. Gubler, and N. Nakicenovic, researchers who have published innovative and challenging analyses of global energy use and substitution patterns. Finally, these pioneers are getting good popular press. A must-have reference for any instructor or student of energy or energy conversion and the environment, and for any government or industry energy analyst or policy maker. Summing Up: Essential. Upper-division undergraduates through professionals; general readers. S. R. Walk Old Dominion University