TiO2-supported gold samples prepared by deposition-precipitation were tested as catalysts for methanol carbonylation to give methyl acetate at atmospheric pressure in the presence of methyl iodide as cocatalyst. Infrared (IR) spectroscopy was used to investigate the reactions of methanol, CO and CH3I on the surface of the samples. The results show the formation of methoxy species bonded to Ti4+ sites upon adsorption of methanol on the supported gold samples. Admission of CO to the flow reactor/IR cell led to the formation of gold carbonyls, which reacted with the surface methoxy species only when CH3I was present to give methyl acetate. The data indicate that CH3I is necessary to form gold-acetyl species, which are attacked by neighboring methoxy species to give the carbonylation product. Our results show that the methanol carbonylation catalyzed by TiO2-supported gold in the presence of CH3I occurs by a reaction mechanism that is similar to that occurring on supported Rh catalysts. (C) 2015 Elsevier B.V. All rights reserved.