An infra-red study of the surface of rutile has been carried out as a function of evacuation temperature (100–500°). Below 400° the surface was found to be composed of isolated and hydrogen bonded OH groups, molecular water being removed by evacuation at temperatures 200°. Above ca. 300° the hydrogen-bonded OH groups were progressively removed, the 450°-treated surface containing only isolated OH groups with a stretching frequency of 3740 cm–1. Absence of oxygen treatment of the surface after high-temperature evacuation markedly affects the OH region of the spectra. Rehydration experiments showed a strong interaction of the evacuated surface with water molecules but it has not been possible to decide conclusively whether surface OH groups are reformed on a 450°-treated surface.