A facile in situ plasma synthesis of graphene-based Pt nanoparticles is presented. For comparison, chemical reduction was also used. Ar plasma was capable of reducing Pt precursors into well dispersed Pt nanoparticles on graphene. The electrocatalytic activities of the two as-prepared catalysts were tested, and then they were used as anodes for methanol electro-oxidation in a DMFC. The catalyst prepared by the plasma approach showed higher catalytic activity for methanol electro-oxidation. The plasma technique is also suitable for the fabrication of other functional carbon based metal composites for their applications in multidisciplinary areas.