Abstract: A single air-breathing direct methanol fuel cell (DMFC) with an active area of 1 cm2 was fabricated and investigated experimentally. A fuel reservoir in anode was used to supply methanol solution. A cathode current collector was designed to integrate the cathode fixture. The fuel cell with a home-made membrane electrode assembly (MEA) was tested. Effects of catalyst type，diffusion layer material，current collector structure and other factors on the cell performance were discussed. The mass transfer characteristics in the fuel cell were also analyzed. Performance of the air-breathing DMFC was optimized especially at high current densities. The results showed that the mass transfer of reactants could be enhanced by using Pt black or Pt-Ru black catalyst. A higher limit current density could be obtained by using carbon cloth as the gas diffusion layer. At low current densities，the cell voltage decreased with an increase in methanol concentration due to the methanol crossover. However，at middle and high current densities，the cell performance increased firstly and then decreased with methanol concentration. The parallel current collector benefits the removal of resultants and the mass transfer of reactants both at the anode and the cathode. Thus，a better cell performance could be achieved by using parallel current collectors.