Sn-activated carbon (Sn-AC) in pressure swing adsorption (PSA) system has been successfully used in the purification of hydrogen for PEM fuel cell application. Activated carbon was impregnated with 34.57 SnCl2.2H2O salt and then dried at 180°C to produce AC-SnO2 to improve its adsorptive interaction with CO. The amount of CO adsorbed was almost equal to that desorbed which could imply that the adsorption of CO on the prepared adsorbents seems to be reversible. Further exploitation of the impregnated activated carbon in PSA experiments showed that adsorption of carbon monoxide was higher with the impregnated carbon than in the pure carbon. The concentration of carbon monoxide, which was 1000 ppm, was successfully reduced to 40.2 and 10.4 ppm by the pure and the impregnated activated carbons, respectively. Besides the fact taht activated carbon has its original different pore sizes for normal gas phase CO adsorption (as in case of pure carbon), the impregnated carbon has additional CO adsorption ability due to the presence of O- (ads) on the active sites. The use of AC-SnO2 in adsorbing CO proved superior to that when pure carbon was used for H2 purification in a PSA system. Discernibly, the high adsorptive selectivity of AC-SnO2 towards gas-phase CO portrays a good future for the applicability of this noble adsorbent, since CO imposes its own threat in the current level of air pollution. (C) 2000 Elsevier Science Ltd. All rights reserved. Sn-activated carbon (Sn-AC) in pressure swing adsorption (PSA) system has been successfully used in the purification of hydrogen for PEM fuel cell application. Activated carbon was impregnated with 34.57 SnCl2.2H2O salt and then dried at 180 °C to produce AC-SnO2 to improve its adsorptive interaction with CO. The amount of CO adsorbed was almost equal to that desorbed which could imply that the adsorption of CO on the prepared adsorbents seems to be reversible. Further exploitation of the impregnated activated carbon in PSA experiments showed that adsorption of carbon monoxide was higher with the impregnated carbon than in the pure carbon. The concentration of carbon monoxide, which was 1000 ppm, was successfully reduced to 40.2 and 10.4 ppm by the pure and the impregnated activated carbons, respectively. Besides the fact that activated carbon has its original different pore sizes for normal gas phase CO adsorption (as in case of pure carbon), the impregnated carbon has additional CO adsorption ability due to the presence of O- (ads) on the active sites. The use of AC-SnO2 in adsorbing CO proved superior to that when pure carbon was used for H2 purification in a PSA system. Discernibly, the high adsorptive selectivity of AC-SnO2 towards gas-phase CO portrays a good future for the applicability of this noble adsorbent, since CO imposes its own threat in the current level of air pollution.