Gold can be compared favorably with Pd and Pt in the catalytic combustion of CH3OH, HCHO and HCOOH when it is deposited on some reducible metal oxides (alpha-Fe2O3, TiO2, etc.). While the supported fold catalysts are less active in H-2 oxidation, they exhibit much higher activities in CO oxidation. For Au/TiO2, the effect of catalyst preparation was further investigated. Since the activity for CO oxidation of the gold catalysts is not depressed but enhanced by moisture, they are practically applicable to CO removal from air at room temperature. Gold supported on manganese oxide is especially effective in the selective CO removal from hydrogen, indicating its potential applicability to polymer electrolyte fuel cells using the reformed gas of methanol.