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 scientific programme included 10 oral sessions and a poster session. Widely based national committees, supported by an International Scientific Advisory Board and the International Coordinators, made every effort to design and bring together a programme of great excellence. The more than one hundred papers submitted represent the efforts of research groups from all over the World. The international character of HYPOTHESIS II has been augmented by contributions coming from seven countries outside Europe. The contributions reflect the progress that has been achieved in hydrogen technology aimed primarily at hydrogen as the ultimate energy vector. This research have already yielded mature technologies for mass production in many areas. These and future results will be of increased interest and importance as global and local environmental issues move higher up the political agenda. In order to facilitate new contacts between scientists and strengthen existing ones, the symposium incorporated an extensive social program managed by the Conference Administrator, Ms. Ann Y stad.