Desorption of hydrogen from the powders of metal hydrides (MH) is affected by several interplaying processes including hydrogen desorption from and recombination on the metal surface, diffusion within the bulk metal and different hydride phases, and decomposition of the hydride phase. In present work, possible mechanisms of hydrogen release from the MH are proposed and discussed. Analytical models are developed which cover common distributed and confluent cases. The models adequately fit the experimental data of the thermal desorption spectroscopy and barometric thermocycling studies. Rate constants of the reactions of hydrogen release from the MH are evaluated on the basis of the fitting of the experimental data by the proposed models. These data are of significant importance in the assessments of suitability of the MH in particular applications.