The metallization of porous solid bodies, such as, for example, ion exchange materials, by loading the surfaces of the metal-free substrates with transition metal ions and subsequently treating them with reducing agents can be improved by activating the substrates, before or after the loading with metal ions, with elements of group 1 or 8 of the periodic table or compounds thereof and sensitizing any activating ions still present. The metallization products are useful hydrogenation catalysts.