[en] Intensive mechanical milling was used to synthesize a MgH₂ (50 wt.%) + TiB₂ (50 wt.%) composite. Thermal stability of the composite versus H-desorption was studied employing the thermodesorption spectroscopy (TDS) method. The TDS data have revealed that TiB₂ addition decreases the dissociation temperature of the MgH₂ hydride by about 50 deg. C. An X-ray photoelectron spectroscopy analysis has shown that TiB₂ addition does not alter the surface chemical state of particles of the MgH₂ hydride, a component of the composite under consideration. The effect of decreasing decomposition temperature of MgH₂ due to addition of TiB₂ has been attributed to catalytic influence of a TiB₂ particle surface on processes of associative hydrogen desorption taking place on the surface of MgH₂ particles, as well as to a higher degree of dispersion of magnesium dihydride provided by the presence of TiB₂