The scope of this paper is to highlight common hazards arising from hydrogen storage and distribution systems, as well as to reveal potential accidents that hydrogen may yield under certain conditions. Hazard analysis performed was based on the Event Tree Analysis Method and examined the final outcomes of an accidental hydrogen release. The output of this analysis was that hydrogen may lead to a series of accident types that can pose a severe threat for property and public safety. Moreover, computational estimation of the dispersion resulting from liquefied hydrogen spills showed that the resulting cloud behaves as a heavy rather than a light gas, remaining in flammable concentrations at low heights above the ground and increasing, therefore, substantially the risk for accidental fires and explosions. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.