Au/Pt bimetallic core/shell nanoparticles that were stabilized by polyaryl ether trisacetic acid ammonium chloride dendrons (G(3)NACl) were synthesized and used as catalysts for the hydrogenation of 3-phenoxybenzaldehyde to 3-phenoxyphenyl methanol and nitrobenzenes to anilines. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-visible absorption spectroscopy revealed that Au/Pt bimetallic nanoparticles with a 6-nm Au core and average overall diameters of 9.0 +/- A 2.4 nm, 10.4 +/- A 2.8 nm, and 13.0 +/- A 3.2 nm for Au75Pt25@G(3)NACl, Au50Pt50@G(3)NACl, and Au25Pt75@G(3)NACl, respectively, had formed. Au/Pt bimetallic nanoparticles showed higher catalytic activity for the hydrogenation of nitrotoluenes to anilines and 3-phenoxybenzaldehyde to 3-phenoxyphenyl methanol as compared to monometallic platinum nanoparticles and physical mixtures of monometallic Pt and Au nanoparticles. The higher activity of the Au/Pt bimetallic nanoparticles may be attributed to the fact that the gold core attracts electrons from platinum. The electron-deficient platinum shell may favor the adsorption of the substrate with polar carboxyl groups.