Selective CO oxidation (PROX) was studied at 423 K over 1% Pt-0.25% SnOx and 1% Pt-1% CeOx catalysts supported on un-oxidized and oxidized activated carbon (AC) using feed mixtures simulating the reformate coming from fuel processors. Effects of the addition of 15% CO2 or (15% CO2 + 10% H2O) into feed mixtures containing 1% CO, 1% O-2, 60% H-2 and He were determined for nine different AC-supported catalysts, and the results were compared with those obtained with pure H-2-rich feed. Unlike other PROX catalysts having oxide supports, introduction of CO2 into pure feed drastically increased CO conversion on all nine catalysts supported on oxidized or un-oxidized AC regardless of impregnation strategy. 1% Pt-0.25% SnOx supported on HNO3-oxidized AC stands out as a potential candidate for commercial use in PROX since it yields 100% CO conversion under realistic feed conditions. 1% Pt-1% CeOx catalysts prepared by sequential or co-impregnation and supported on air-oxidized AC also give 100% CO conversion in H-2-rich feed containing (CO2 + H2O) during extended run times and hence hold promise as PROX catalysts. (c) 2006 Elsevier B.V. All rights reserved.