In the frame of the EC-funded project HYPER [1] Pro-Science GmbH performed distribution and combustion experiments on the hazard potential of a severe hydrogen leakage inside a fuel cell cabinet using a generic enclosure model with the dimensions of a commercially available fuel cell application. Hydrogen amounts from 1.5 to 15 g were released within 1 s into the enclosure. In distribution experiments the effects of different venting characteristics and different amounts of internal enclosure obstruction on the hydrogen concentrations measured at fixed positions in- and outside the model were investigated. Subsequently combustion experiments with ignition positions in- and outside the enclosure and two different ignition times were performed. BOS (Background-Oriented-Schlieren) observation combined with pressure and light emission measurements were performed to describe characteristics and hazard potential of the induced hydrogen combustions. The experiments provide new experimental data on the distribution and combustion behaviour of hydrogen releases into a partly vented and partly obstructed enclosure with different venting characteristics. (c) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.