A method for oxidizing carbon monoxide (CO) and volatile organic compounds (VOCS) comprises contacting a gas containing water vapor and said CO and VOCs with a catalyst composition comprising at least one base metal promoter and at least one base metal catalyst supported on an oxide support material comprising one or more of alumina, silica, zirconia, ceria, and titania, wherein the VOCs comprise one or more of methyl acetate, methane, methyl bromide, benzene, methanol, methyl ethyl ketone, butane, and butene.