A polymetallic nanoparticle alloy having enhanced catalytic properties including at least one noble metal and at least one base metal, where the noble metal is preferentially dispersed near the surface of the nanoparticle and the base metal modifies the electronic properties of the surface disposed noble metal. The polymetallic nanoparticles having application as a catalyst when dispersed on a carbon substrate and in particular applications in a fuel cell. In various embodiments a bimetallic noble metal-base metal nanoparticle alloy may be used as an electrocatalyst offering enhanced ORR activity compared to the monometallic electrocatalyst of noble metal.