This volume contains selected contributions to the Second Hydrogen Power, Theoretical and Engineering Solutions, International Symposium (HYPOTHESIS II), held in Grimstad, Norway, from 18 to 22 August, 1997. The more than 100 papers submitted to this conference represent the efforts of research groups from all over the world. The contributions reflect the progress that has been achieved in hydrogen technology aimed primarily at hydrogen as the ultimate energy vector. This research has already yielded mature technologies for mass production in many areas. These results will be of increased interest and importance as global and local environmental issues move higher up the political agenda. This volume yields a comprehensive review of the most relevant areas of hydrogen technology, making it an asset for all researchers and students interested in these subjects. The papers are organized into the following sections: transportation, hydrogen production, hydrides, safety, hydrogen systems, liquid hydrogen and fuel cells.