The course of MgH2 hydrolysis strongly depends on pH of the reaction solution: the 100% yield can be achieved at pH below ~4.5 for the acetic and citric acids and below ~2 for the oxalic acid. For the citric and acetic acids, the pH after hydrolysis changes insignificantly with the increase of acid concentration that testifies about buffer nature of the solutions "citric acid / magnesium citrate" and "acetic acid / magnesium acetate".