Structure-controlled metallic catalysts have been well known to exhibit an improved electrocatalytic activity due to modulated surface structures favorable for electrochemical reactions. We have synthesized Pt–Rh nanodendritic catalyst for methanol electrooxidation by a polyol method in the presence of PVP and l-ascorbic acid in aqueous solution. The as-synthesized Pt–Rh alloy nanoparticles exhibited a dendritic structure with well-defined alloy formation between the Pt and Rh metallic phase, uniform particle size and shape, and high-index facets. Furthermore, we found remarkably improved electrochemical properties of the Pt–Rh alloy nanodendrites i.e. improved electrocatalytic activity and stability for methanol electrooxidation in comparison with spherical Pt–Rh and pure Pt nanoparticles.