Oxidized nano-porous-silicon (ONPS) thin films were prepared by rapid-thermal oxidization of nano-porous silicon films that were formed on Si substrates with an anodization technology. The ONPS films exhibited high responsivity for incident ultra-violet (UV) light with wavelengths between 300 nm and 400 nm. Under illumination of incident 350 nm UV light and 5 V bias, the ONPS-based photodiodes obtained a high photo current of 3.24 mA/cm(2) and large photo-to-dark current ratio of 300, indicating that the ONPS thin films have significant potential for applications of UV optical-sensing devices. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.