Oxidation processes of magnesium and magnesium "mechanical alloys" with iron and copper (1-15 wt%) in presence of aqueous solutions of sodium, cobalt, nickel and copper chlorides have been investigated. The rate of hydrogen generation increases with the increase of the transition metal content in the "alloys" and levels out for the Mg-Cu system. The overall hydrogen yield does not exceed 92% of theoretical one at the initial solution concentrations of 0.032 M and chloride/Mg molar ratios of 0.0075 (0.85 M and 0.20 for NaCl), but becomes close to 100% at double concentration of the transition metal salt solutions. The electrochemical corrosion mechanism of the magnesium oxidation process has been suggested. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.