Enhancing catalytic selectivity of supported metal nanoparticles with capping ligands is demonstrated using an Au/SiO(2) catalyst in liquid phase aerobic oxidation of benzyl alcohol. Chemisorption of an appropriate amount of polyvinylpyrrolidone on the Au/SiO(2) catalyst greatly enhances the benzaldehyde selectivity from 43% to ~100% and its yield from 4.9% to 7.2%.