For the first time, the high-yield, branched Rh/Pt bimetallic ultrathin nanowires with nodes and stems have been synthesized by seed displacement, epitaxial growth method in aqueous solution containing Rh nanocubes seeds, K2PtCl6, and poly(vinyl pyrrolidone) (PVP). The quantities of Rh nanocubes play a key role in the formation of high-yield ultrathin nanowires. The results of EDS line scanning and elemental analysis map have shown that the Rh atoms distribute discretely in the wires. The electrocatalytic properties of the Rh/Pt bimetal alloys, Rh nanocubes, and commercial Pt black toward ethanol oxidation have been investigated. The Rh/Pt ultrathin nanowires have displayed enhanced electrocatalytic performance and selectivity. The results of in situ FTIR have shown that the selectivity to the complete oxidation of ethanol to CO2 of Rh/Pt bimetallic ultrathin nanowires is at least 2.69 times higher as compared with the commercial Pt black.NSFC [20725102, 20933004, 20921001]; Fok Ying Tung Education Foundation [111012]; State Key Project of Fundamental Research for Nanoscience and Nanotechnology [2006CB932301