Abstract
Oxide materials play an important role in technical applications such as gas sensing and catalysis, where they can react notably with water in vapor or liquid form. We find that the coverage of *OH measured at fixed relative humidity trends with the electron donor (basic) character of wetted perovskite oxide surfaces, corresponding to low contact angles when removing a droplet of water. We report for the first time that the affinity toward hydroxylation, coincident with strong adsorption energies calculated for dissociative and molecular adsorption of water, leads to strong H-bonding detrimental to catalysis of the oxygen reduction reaction (ORR). This suggests that hydrophobic oxides with low tendency to hydroxylate may demonstrate improved catalytic activity for the ORR.