PtRh alloy nanoparticles were synthesized for use in enhancing the stability of methanol crossover and electrocatalytic activity for oxygen reduction in direct methanol fuel cells (DMFCs). From the electrochemical results, by comparing Pt in terms of methanol tolerance and oxygen reduction with Pt-based alloys, the PtRh(2:1) was an optimum catalyst for the elimination of CO poisoning during the oxidation of crossover methanol as well as oxygen reduction. A PtRh(2:1) alloy cathode showed a higher power density as well as better performance stability than Pt in DMFC unit cell test.