To analyse beat and mass transfer in a metal-hydrogen reactor, the hypothesis that disregards the radiative heat transfer in the reactor, is typically used. In this paper, we take into account the radiative heat. transfer and we test the validity of this hypothesis in the case of the LaNi5 and in the case of the magnesium. A theoretical model is conducted for the two-dimensional system where conduction, convection radiation and chemical reaction take place simultaneously. This model is solved by the finite volume method. The numerical simulation is used to present the time-space evolutions of the temperature and the hydride density in the reactor and to determinate the sensitivity to some parameters (absorption coefficient, scattering coefficient, reactor wall emissivity). (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.