There is provided a method of preparing carbon supported, ternary alloy composition core-shell PtVFe nanoparticles for use as fuel cell electrocatalysts. These catalysts have been found particularly useful for oxygen reduction reactions. The alloy nanoparticles can be assembled on carbon supports which then may undergo subsequent activation and/or calcination treatments. The method, combined with new synthetic feed and processing conditions, provides core-shell PtVFe alloy nanoparticles of 1 3 nm size. The catalyst-produced high monodispersity, controlled composition are highly dispersed, and have a uniform distribution. Finally, the correlation of the preparation and treatment parameters to the ORR catalytic activities of the prepared nanoparticles is described. The catalysts exhibit ORR in the range of 2 to 4 times more than a standard Pt/carbon catalyst.