Active species such as holes, electrons, hydroxyl radicals ((OH)-O-center dot), and superoxide radical anions (O-2(center dot-)) involved in the photocatalytic oxidation of benzyl alcohol (BA) into benzaldehyde (BAD) on TiO2 under ultraviolet (UV) light were investigated by adding corresponding scavengers. The experimental results show that the oxidation of BA into BAD is driven mainly by the holes and (OH)-O-center dot radical. The role of dissolved O-2 was studied by bubbling N-2 through the reaction. The results show that the dissolved O-2 is, to some extent, the source of (OH)-O-center dot. Additional density functional theory (DFT) calculations identified two H-abstraction pathways (RabsOH and R-abs alpha). The structure of the RabsOH product is less stable and tends to transfer resulting in the R-abs a product. The holes are the main driving force for the abstracting of H from BA. The (OH)-O-center dot radical combines with the H-abstract product to form a precursor of product BAD, detected by LC-MS technique (m/z 123), which then undergoes an intramolecular dehydration reaction to form BAD. The results will help to select the optimal active species for the photocatalytic oxidation of BA into BAD on TiO2 under UV light. (C) 2016 Published by Elsevier B.V.