The reduction of NO with H-2 and the oxidation of CO with O-2 were investigated over silica- and alumina supported gold/metal oxide catalysts (M: Co, La, Ce). In general, the silica supported samples were less active than the alumina supported ones, probably due to the presence of large gold particles. The presence of metal oxide was beneficial to the activity in the NO/H-2 reaction and the CO/O-2 reaction over Au/SiO2. Opposite behavior was observed with the NO reduction over Au/Al2O3 where the metal oxide might cover active species. Addition of cobalt oxide and lanthana improves the selectivity towards N-2.