SummaryAdsorption isotherms, the infrared spectra of adsorbed species, and the amount of hydroxyl released when oxalate is adsorbed, all indicate that adsorption of oxalate, benzoate and phosphate at low solution concentrations occurs only on A1(OH)(H2O) sites exposed on edge faces of the platy gibbsite crystals studied. This is confirmed by the finding that the vibrations of surface hydroxyl groups on the principal plate faces are unaffected when excess oxalate is present, and further supported by the low affinity for oxalate of imogolite, a tubular mineral with a very large gibbsite‐like surface, but with a very low concentration of edge sites.Infrared spectra indicate that oxalate is adsorbed in bidentate form. Near neutrality and at low solution concentrations, gibbsite adsorbs more oxalate than does goethite of comparable surface are