The possibility of using a risk based approach for the safe installation and siting of stationary fuel cell systems depends upon the availability of normative data and guidance on potential hazards, and the probabilities of their occurrence. Such guidance data is readily available for most common hydrocarbon fuels. For hydrogen, however, data is still required on the hazards associated with different release scenarios. This data can then be related to the probability of different types of scenarios, from historical fault data, to allow safety distances to be defined and controlled using different techniques. Some data on releases has started to appear but this data generally relates to hydrogen vehicle refuelling systems that are designed for larger throughput, higher pressures, and the general use of larger pipe diameters than are likely to be used for small fuel cell systems. The aim of this paper is to report on work that is providing data for informing safety distances for high-pressure components/fuel cell systems and associated fuel storage. Using high-pressure release scenarios, the extent of the clouds, jets and, following ignition, fires and explosions were investigated. (c) 2010 Published by Elsevier Ltd on behalf of Professor T. Nejat Veziroglu.