The reaction of H2S with chromium, chromia, and Au/chromia films grown on a Pt(111) crystal has been investigated using synchrotron-based high-resolution photoemission spectroscopy. At 300 K, H2S completely decomposes on polycrystalline chromium producing a chemisorbed layer of S that attenuates the Cr 3d valence features, No evidence was found for the formation of CrSx species. The dissociation of H2S on Cr3O4 and Cr2O3 films al room temperature produces a decrease of 0.3-0.8 eV in the work function of the surface and significant binding-energy shifts (0.2-0.6 eV) in the Cr 3p core levels and Cr 3d features in the valence region. The rate of dissociation of H2S increases following the sequence: Cr2O3 H2S(5a(1),2b(1)) bonding interactions and facilitates the decomposition of the molecule. (C) 1997 American Institute of Physics.