Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy is used to characterize the adsorbed species when zirconia is exposed to aqueous oleate and oleic acid over a range of pH. The results show that, at pH 9, both oleate anions and oleic acid dimer are adsorbed. The adsorption of oleate anions at a pH where the surface is negatively charged contravenes expectations based on simple electrostatics and indicates another driving force for adsorption, most probably the coordination of oxygen lone pair electrons into zirconium vacant 3d orbitals. At pH 3 both oleate anions and oleic acid monomer are adsorbed with the spectra indicating that H-bonding between C=O groups and surface ZrOH2+ groups contributes to the adsorption of the latter. The intensity distribution in the CH3/CH2 stretch bands of oleate/oleic acid adsorbed at pH 3 differs from that in pure oleic acid. This is tentatively attributed to interactions between the hydrocarbon tails and the protonated surface.