This study aims to analyze the oxidation of carbon monoxide in moist air from the second thermodynamic law aspect. A mathematical model of laminar premixed ame in a stagnation point ow has been achieved by numerical solution of the boundary layer equation using a self-made code. The chemical kinetic mechanism for ameless combustion of fuel, which is a mixture of carbon monoxide, oxygen, and water vapor, is modeled by 34 elementary reactions that incorporate (09) nine chemical species: CO, O, CO 2 , O 2 , H 2 O, H, H 2 , HO 2 , and OH. The salient point is that for all the parameters we considered, the exergy of the process is completely destroyed by irreversibilities. From the chemical viewpoint, the OH radical plays an essential role in CO oxidation. This latter point has already been mentioned by previous investigators.