The proton exchange membrane fuel cell (PEMFC) is one of the most promising power sources for stand-alone utility and electric vehicle applications. Platinum (Pt) catalyst is used for both fuel and air electrodes in PEMFCs. However, carbon monoxide (CO) contamination of H-2 greatly affects electrocatalysts used at the anode of PEMFCs and decreases cell performance. The irreversible poisoning of the anode can occur, even in CO concentrations as low as a few parts per million (ppm). In this work, we synthesized several novel electrocatalysts (Pt/C, Pt/Ru/C, Pt/Mo/C, Pt/Ir, and Pt/Ru/Mo) for PEMFCs. These catalysts were tested for CO tolerance in the H-2/air fuel cell, using CO concentrations in the H-2 fuel that varies from 10 to 100 ppm. The performance of the electrodes was evaluated by determining the cell potential against current density. The effects of catalyst composition and electrode film preparation method on the performance of PEM fuel cell were also studied. It was found that at 70degreesC and 3.5-atm pressure at the cathode, Pt-alloy catalyst (10 wt% Pt/Ru/C, 20 wt% Pt/Mo/C) were more CO tolerant than the 20 wt% Pt/C catalyst alone. It was also observed that the spraying method was better than the brushing technique for the preparation of electrode film.