The adsorption and surface reactions of acetonitrile and acetonitrile-oxygen gas mixture were studied on TiO2-supported Au catalysts at 300-673 K. FTIR spectra show different kinds of molecularly adsorbed CH3CN:acetonitrile can be bonded to weak Lewis acid sites (2295 cm(-1)), to strong Lewis acid sites (2337 cm(-1)) of titania; it can be coordinated linearly through the lone electron pair of the N atom on Au sites and eta(2) (C,N) CH3CN species can be formed on Au particles. CH3CN dissociates on Au sites, the resulting CN(a) can be oxidized in small extent by lattice oxygen and in a greater extent by gaseous oxygen into NCO surface species. The formation of other products (CH3NH2, H-2, CO2, CH4, C2H4 and CO) was demonstrated and discussed.