We have used temperature programmed desorption (TPD) and Auger electron spectroscopy to study H(2)0-Cl-2 interactions on an iron oxide surface under ultrahigh vacuum conditions over the temperature range 90-900 K. On the clean Fe oxide, the TPD spectra of H2O show two desorption peaks at 175 and at 250 K. No H-2 desorption is observed. This is in contrast to other studies of H2O on a sputtered alpha-Fe(2)O3 (001) plane that indicate the complete dissociation of H2O, leading to H atoms, which then recombine resulting in H-2 desorption (220-750 K). The Fe oxychloride [Fe(OCl)(x)] formation that occurs at low temperatures (240 K) at the Fe polycrystalline surface as a result of H2O-Cl-2 interactions does not occur on the Fe oxide surface. FeCl2 desorption is observed at temperatures significantly higher (695 K) than the temperature for the desorption of FeCl2 from metallic Fe (585 K). On the Fe oxide surface, FeCl2 desorption is independent of H2O precoverage, in contrast to results on the Fe surface that show inhibition of FeCl2 formation with increasing H2O preexposure. These results indicate the presence of different sites on the oxide surface for the preferential adsorption of Cl-2 and H2O, in agreement with our previously reported x-ray photoelectron studies.