Large quantities of single-crystal silicon oxynitride (SiOxNy) nanowires were synthesized on silicon substrate by a vapor-solid mechanism without using any catalyst. These single crystalline nanowires are 50 to 200 nm in diameter, and a few hundreds of micrometers to several millimeters in length with high N concentration. The obtained SiOxNy nanowires are attractive by their exceptional whiteness, perceived brightness, and optical stability at high temperature. The experimental results show that the nanowire mat displays strong diffusive reflection over the whole visible wavelength, with more than 80% of light reflected at the wavelength range from 400 to 780 nm. It is also demonstrated that the grown nanowires can be applied as coating material over reflector cup surface for white light-emitting diode lamp. It is shown that trapped modes can be significantly reduced by increasing the diffuse reflectivity of the reflector cup thus improving the lighting efficiency. (C) 2012 Elsevier B.V. All rights reserved.