TiO2 and ZrO2 nanocrystals were successfully synthesized and deposited onto wool fibers using the sol-gel technique at low temperature. The photocatalytic activities of TiO2-coated and ZrO2-coated wool fibers were measured by studying photodegradation of methylene blue and eosin yellowish dyes. The initial and the treated samples were characterized by several techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and X-ray diffraction. The TEM study shows dispersed particles with 10-30 nm in size for TiO2-coated and 20-40 nm in size for ZrO2-coated samples on the fiber surface. Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO2 modified sample with respect to that of ZrO2 for degradation of both dyes. Our observations indicate that by applying this technique to the fabrics, self-cleaning materials could be designed for practical application. (C) 2010 Elsevier B. V. All rights reserved.