A facile, reliable, general, and robust synthetic method for preparation of high-quality, (100)-terminated Pt3M nanocubes (M = Pt or 3d-transition metals Co, Fe, and Ni) has been developed. It was identified that addition Of W(CO)(6) is crucial for control of the nucleation process when the metallic precursors are reduced, whereas an optimized ratio of the solvent pair, oleylamine and oleic acid, is the key to enabling the lowest total surface energy on {100} facets in order to develop cubic nanocrystals in the present system. The resultant monodisperse nanocubes, in which Pt is partially substituted, are expected to exhibit unusual electrocatalytic characteristics, providing an alternative for developing high-performance electrocatalysts for use in fuel cells.