XRD analysis of the deposits after hydrolysis (Figure )) showed that after hydrolysis in de-ionized water (Figure (a)) the residue contains unreacted α-MgH2, Mg and Mg(OH)2. At the same time, the residues after hydrolysis of MgH2 in 1 wt.% aqueous organic acid solutions only contain very well crystallized (narrower lines as compared to the starting/commercial MgH2) unreacted MgH2+Mg and no Mg(OH)2. This is expected for the acetic and citric acids, as Mg(OH)2 reacts with them to form well-soluble magnesium acetate and citrate. Somewhat surprising is a fact that the poorly soluble magnesium oxalate (see Table ) was not found in the XRD pattern. The reason for that appears to be in amorphous nature of its deposit, or in a formation of super-saturated solution containing (MgC2O4)n molecules (n=1-3) .