High concentrations of certain 1-1 electrolytes in water induce a shift in the isoelectric point (IEP) of metal oxides to pH values substantially higher than the pristine IEP. With large cations, the nature of the anion does not affect the magnitude of these shifts, but with Li and Na the shift depends on the nature of the anion. This effect is termed the differentiating effect of small cations, and it has been studied in detail for anatase. The present results confirm the existence of the differentiating effect of Na for alumina. The anion sequence I > Br > Cl > ClO4 > NO3 observed for alumina is identical with that reported for anatase,