The 2003 International Conference "Hydrogen Materials Science and Chemistry of Carbon Nanomaterials" was held in September 2003. In the tradition of the earlier ICHMS conferences, this meeting served as an interdisciplinary forum for the presentation and discussion of the most recent research on transition to hydrogen-based energy systems, technologies for hydrogen production, storage, utilization, materials, energy and environmental problems. The aim of the volume is to provide an overview of the latest scientific results on research and development in the different topics cited above. The representatives from industry, public laboratories, universities and governmental agencies have presented the most recent advances in hydrogen concepts, processes and systems, to evaluate current progress in these areas of investigations and to identify promising research directions for the future.