The ability to simulate the whole chain of physical phenomena that may occur following an accidental hydrogen release is mandatory for future safety studies on an industrial or urban scale. In cooperation with the RWTH Aachen University, Forschungszentrum Julich develops numerical methods to predict safety incidents connected with the release of either liquid hydrogen (LH2) or gaseous hydrogen (GH(2)), using the commercial computational fluid dynamics (CFD) code ANSYS CFX. The full sequence from the release, distribution or accumulation of accidentally released hydrogen, until the mitigation of accident consequences by safety devices is considered. The paper describes the current development status, gives examples of the validation and concludes with future work to provide the full range of hydrogen release and recombination simulation. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.