Nanocrystalline aerogel TiO2 photocatalysts prepared by a facile epoxide sol-gel synthesis followed by subsequent supercritical drying and thermal processing were studied in regard to their performance in the photocatalytic degradation of phenol. Xerogel TiO2 catalysts obtained by direct drying were also examined. A variety of techniques including N-2 adsorption, XRD, DRIFTS, TEM, and DR UV-vis were employed to characterize the microstructural and surface properties of the as-obtained aerogel and xerogel TiO2 samples. It is shown that the aerogel samples showed particular advantage in controlling the microstructural properties in terms of crystallite size, surface area, crystallinity as well as anatase and rutile phase composition, which are responsible for the high activity of these photocatalysts. The aerogel sample obtained by calcination at 650 degrees C afforded the highest specific activity for photodegradation of phenol, which is also found to be far superior to that of the commercial photocatalyst Degussa P-25. (c) 2006 Elsevier B.V. All rights reserved.