The effect of the pretreatment on the interaction between NO and Au-TiO2 was examined using DRIFTS as a monitoring tool. For calcined and reduced Au-TiO2, adsorption of NO on the TiO2 support is not promoted under the conditions employed. Au(NO)(2) is the predominant species on oxidized and reduced Au-TiO2 With initial bands at 1818 and 1740 cm(-1). Analysis showed that these species are sensitive to the surface coverage, temperature, and the state of the underlying surface, shifting from 1820 cm(-1) for reduced Au-TiO2 to 1850 cm(-1) for oxidized Au-TiO2 and from 1740 to 1734 cm(-1) with increasing surface temperature. It is proposed that different dinitrosyl components are formed on the surface and are bonded to Au sites in different chemical environments. Small dissociative contributions (N2O formation) were detected at higher NO pressures and temperatures. Adsorption of NO on oxidized Au-TiO2 is dominated by bridging NO adsorbates (bands at 1665 and 1641 cm(-1)) at low NO exposures, but linearly bound NO (bands at 1873, 1860, 1838, and 1808 cm(-1)) were detected with increasing NO coverage. Products of dissociation and associated mainly with the TiO2 support dominate the spectra for oxidized Au-TiO2.