Numerical simulations have been conducted for large scale hydrogen detonation by solving Euler equations with a single step reaction for the chemistry. A total variation diminishing numerical scheme is used for shock capturing. Predictions were firstly conducted with a small domain to ensure that the reaction scheme has been properly tuned to capture the correct detonation pressure and velocity. On this basis, simulations were conducted for the detonation tests carried out at Kurchatov Institute in Russia [1,4]. Comparison is made between the predictions and measurements. Further simulations were then conducted for a hypothetical hydrogen-air cloud in the open to assess the impulse as well as overpressure distributions. (c) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.