Hydrogenation processes are of paramount importance in the interstellar medium. Many laboratory experiments were carried out from unsaturated species. Herein, the hydrogenation of hydrogen peroxide was experimentally investigated step by step by means of the matrix isolation technique. This reaction leads to the formation of water. Moreover, the formation of H3O2 and OH radicals as intermediates was characterized. Such a hydrogenation process should take place on the surface of dust grains in the interstellar medium. This reaction is consistent with the very small amount of interstellar hydrogen peroxide. This hydrogenation process also takes place in solid phase.
