A series of Pt x Ni/C (x=1–3) nanoparticle catalysts were prepared using a chemical reduction method, where the aim was to reduce the Pt loading and maintain high catalytic reactivity towards the oxygen reduction reaction. The catalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical performance of the Pt x Ni/C alloy catalysts was evaluated by cyclic voltammetry, steady-state measurements, and chronoamperometric testing. We found that the catalytic reactivity of Pt catalysts towards oxygen reduction can be maintained or even enhanced by partially replacing platinum with nickel.