The experimental study of catalytic activity of transition metals Ti and Ni for the hydrogenation process was carried out. Magnesium was used as hydride material, and carbon was used for stabilization of obtained systems. Nanocomposites Mg-C, Mg-Ti-C, Mg-Ni-C were synthesized by plasma-chemical method. The hydrogenation of all types of nanocomposites were carried out during the synthesis process. Nanocomposites Mg-Ti-C and Mg-Ni-C were hydrogenated also under pressure. Hydrogenation was carried out under pressure (6 MPa) for 20 minutes. Dehydrogenation process was carried out by heating until 700 °C with the rate of 1 °C an second. The magnesium hydride formation was only in the Mg-Ni-C, for samples obtained during nanocomposite synthesis. For samples of nanocomposites obtained under pressure, the temperature began to decomposition of magnesium hydride in nanocomposites Mg-Ni-C was 300 ° C, in the Mg-Ti-C - 450 ° C. Thus, nanocomposite Mg-Ni-C creates the best conditions for the dehydrogenation of hydrogen.