Activated carbon fibers (ACFs) supported TiO2 Photocatalyst was successfully prepared by a molecular adsorption-deposition (MAD) method followed by calcination in a stream of Ar gas. The photocatalyst developed was characterized by SEM, XRD, XPS, BET surface area and UV-vis adsorption spectroscopy. SEM observation showed TiO2 was deposited on almost each carbon fiber with a coating thickness of about 100 nm, and the space between adjacent fibers was remained unfilled to allow UV light to penetrate into the felt-form photocatalyst to a certain depth. Anatase-form TiO2 was uniquely developed even as calcination temperatures rose up to 900degreesC. Tight contact of thin TiO2 coating to carbon fibers surfaces was supposed to suppress phase transformation of TiO2 from anatase to rutile, and to keep high crystallinity of anatase. As confirmed by XRD and XPS examinations, the micrographic structure and surface properties of ACFs had not been damaged by the deposition process and calcination at high temperatures. The present photocatalyst showed high photocatalytic reactivity in photodegradation of highly concentrated methylene blue (MB) solutions. The comparative experiments indicated the photocatalyst produced had a combined effect of photocatalytic reactivity of anatase-type TiO2 with adsorptive property of activated carbon fibers. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed. (C) 2004 Elsevier B.V. All rights reserved.