Fuel cells are promising sustainable energy conversion devices. Before widespread commercialization, several key properties of fuel cells must be optimized. One method used for improving fuel cell performance is electrospinning sub-micron diameter fiber electrodes. Electrospun catalyst/binder fiber mat cathodes were found to be highly porous, with a high catalyst surface area and improved gas transport to catalyst sites. Building on previous research at Vanderbilt that used electrospinning for fiber mat fuel cell fabrication, the present study was carried out to investigate catalytically active platinum alloy particles for the cathode in a hydrogen/air fuel cell. One alloy, PtCo has been shown to be more active than Pt for oxygen reduction, based on rotating disk experiments in the literature. To confirm the advantage of this catalyst, PtCo in nanofiber mat cathode membrane-electrode-assemblies were fabricated and tested. Experimental results show a 30% improvement in maximum fuel cell power output, as compared to the use of a convention Pt/C cathode catalyst.