The present invention discloses a method for removing carbon monoxide (CO) from a gas mixture containing CO including contacting the gas mixture with a nano-gold catalyst to reduce the CO content in the gas mixture by CO selective adsorption/oxidation, water gas shift reaction or CO selective oxidation reaction. The nano-gold catalyst includes a solid support and gold deposited on the support, wherein the deposited gold has a size less than 10 nm, and the support is a mixed metal hydroxide and oxide having the following formula: M(OH)qOy Wherein M is Ti, Fe, Co, Zr, or Ni; q is 0.1-1.5; and q+2y=z, wherein z is the valence of M.