The aim of the present work is to assess the risk of explosion of {H2 / O2 / N2} mixtures through the characterization of their fundamental combustion properties: (i) laminar flame speed (SL°), maximum combustion pressure (PMAX) and pressure rise (dP/dt)MAX in a spherical vessel ; (ii) detonation speed and cell size using a cylindrical detonation tube. Equilibrium calculations were made to obtain: (i) theoretical maximum pressure (PAICC), (ii) the Theoretical Chapman-Jouguet detonation velocity. Simulated laminar flame speeds using COSILAB have been obtained. A suitable model has been selected in order to determine the activation energy of these mixtures. The proportionality factor between the detonation cell size and the induction length has been derived based on the ZND model and using a detailed kinetic mechanism.