Carbon monoxide (CO) removal is an important issue for applications involving purification, separation, and catalysis. In this study, CO separation from gas mixtures containing H_2, CH_4, and CO_2 via adsorption by Cu-impregnated activated carbon (Cu / AC) was investigated. The CO adsorption equilibria and kinetics for the Cu / AC were determined, and the adsorption isotherms and dynamic curves established using mathematical models. Breakthrough tests of CO adsorption by a Cu / AC adsorbent bed were also examined. The experiment results reveal that the maximum CO adsorption capacity of Cu / AC at 298 K and 0.1 MPa is 2.25 mmol/g, four times higher than that of pristine AC (0.58 mmol/g). The π-complexation bonding with heat of adsorption of about -40 kJ/mol is considered the major cause of the enhanced CO adsorption by the Cu / AC adsorbent. Moreover, the Sips model and the pseudo-second order model are useful for describing the CO adsorption equilibria and kinetics of Cu / AC. This indicates heterogeneous adsorption and strong interaction between Cu (I) and CO. Moreover, the adsorption breakthrough test shows that the CO could be efficiently removed and reduced several thousand times from percentage level to ppmv level, under ambient conditions (298 K and 0.1 MPa).