Spontaneous ignition of a pressurized hydrogen release has important implications in the risk assessment of hydrogen installations and design of safety measures. In real accident scenarios, an obstacle may be present close to the release point. Relatively little is known about the effect of such an obstacle on the salient features of highly under-expanded hydrogen jets and its spontaneous ignition. In the present study, the effect of a thin flat obstacle on the spontaneous ignition of a direct pressurized hydrogen release is investigated using a 5th-order WENO scheme and detailed chemistry. The numerical study has revealed that, for the conditions studied, the presence of the obstacle plays an important role in quenching the flame following spontaneous ignition for the release conditions considered. (c) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.