Tenfold enhancement in catalytic activity of platinum supported by carbon black for methanol oxidation was achieved by doping with single walled carbon nanotubes less than 2wt% of catalyst composite. The catalytic activity enhancement is attributed to the increase of catalyst utilization by improving interconnectivity among carbon blacks. This complies with the morphology, conductivity, and durability enhancement of the catalyst composites. Enhancement of the catalytic activity by doping a small fraction of carbon nanotubes into the catalyst composite is very promising as a highly efficient and cost-effective catalyst.