The effects of the addition of the inorganic salts NaF, NaCl, MgF2 or CrCl3 on the hydriding and dehydriding behavior of Mg and Mg–Ni mechanical alloys were investigated. It has been found that some inorganic salts, being mechanically alloyed with magnesium or magnesium alloys, not only promote metal powdering but also modify the metal surface. This leads to an acceleration of the hydriding and dehydriding reactions of these materials and to quite high hydrogen capacities (∼5.5–6 wt.%). The investigated salts had different influences on the metal surface properties, which was reflected in reaction kinetics, in particular at first hydriding.