The increase of acid concentration to 0. The 100% reaction yield accompanied by complete dissolution of MgH2-GLM and MgH2-Ni/GLM composite in the citric acid solution was observed at Acid/MgH2 molar ratio equal to or higher than 1. In doing so, pH of the solution after hydrolysis at Acid/MgH2 (mol) of 1 and 2 was equal to 3.5 and 2.6, respectively. This observation is in line with the results of our studies of hydrolysis of commercial MgH2 in citric acid solutions (see Section 3.2) according to which the hydrolysis is completed at Acid/MgH2 (mol)>0.9, and the final pH for Acid/MgH2 (mol)=0.82 was equal to 4.53.