Carbon-supported PtNi nanoparticles have been prepared from the thermolysis of a single source precursor [(bipy)(3)Ni](PtCl6). The single source precursor is highly stable under ambient conditions, allowing easy materials handling and storage. The carbon-supported PtNi nanoparticles had a mean diameter of 8.3 nm and were obtained by a two-stage process involving (i) the ballmilling of carbon and the precursor and (ii) the thermal degradation of the homogenized mixture at 550degreesC in a flowing H-2/Ar gas mixture. The carbon-supported bimetallic nanoparticles were characterized by powder X-ray diffraction scanning electron microscopy-energy-dispersive X-ray, and transmission electron microscopy. The electro-oxidation of methanol over this catalyst was investigated and benchmarked against a commercial E-TEK Pt/C catalyst. The catalytic activity was higher for this homemade catalyst, which also displayed improved resistance to catalyst deactivation. (C) 2004 The Electrochemical Society.