To examine the effect of metal nanostructures on the photoluminescence of CdS nanoparticles, Au/SiO2 nanocomposites were prepared with back-reflection geometry. The contribution from the prolonged optical-path lengths was excluded, and the luminescence enhancement was attributed only to surface-plasmon resonance. The optimum nanostructures for the PL enhancement were examined, and correlated with the wavelength of the surface-plasmon peak of the Au/SiO2 nanocomposites and the PL emission peak of CdS nanoparticles. (C) 2011 Elsevier Ltd. All rights reserved.