Hydrogen sorption characteristics were investigated in Mg modified by ten chosen catalyzing additives X = Mg2Si, Mg2Ge, Mg17Al12, Mg5Ga2 , NaCl, LiCl, NaF, LiF and by two combinations Ni + Mg(17)Al(12 )and Ni + Mg2Si. Amorphous carbon (CB) was used as an antisticking component. It was found that optimum content of both X and CB was between 10 and 14 wt %. To assess the effect of X itself upon the sorption kinetics, concentration of both X and CB was fixed to about 12 wt %. The shortest desorption times t(09) (time to desorption of 90 pct of stored hydrogen) showed alloys with X = NaF, Mg2Si, Mg2Ge and NaCl. Careful measurements of equilibrium hydrogen pressure, p(eq) at 623 K showed an increase in p(eq) for added chlorides, fluorides, Mg2Ge and also for Mg2Si. TPD experiments revealed desorption peaks for X = NaCl, LiF shifted down to temperatures as low as 597 K. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.