Adsorption of chromium, nickel and cobalt on porous glass was examined at 298 K. These metals were adsorbed by ion-exchange from exchange solutions that did not contain any ammine complex ions. It was considered that adsorbate ions were aqua ions of these metals and, in the cause of chromium, also Cr (OH)(2+) ion. Much more chromium was adsorbed from the non-equilibrium exchange solution soon after preparation than from the exchange solution at chemical equilibrium, because chromium underwent hydroxylation for six days. Chromium was adsorbed in the pH 2.7 to 3.3 region and nickel and cobalt were adsorbed in the pH 4.0 to 6.4 region. Thus, the pH region of adsorption differed with the charge carried by the metal.