We investigated the chemical state and environment of Cr ions in a Cr ion-grafted TiO2 photocatalyst by means of X-ray absorption fine structure (XAFS) measurements. The XAFS results indicated that the Cr ions exist on TiO2 as Cr(III) in an amorphous Cr2O3-like structure. The Cr2O3-like structure formed clusters and attached to the TiO2 surface. The activity (CO2 generation rate and QE value) was evaluated by 2-propanol decomposition under visible light (1 mW cm(-2), 450-580 nm) and was highest with a weight fraction of Cr/TiO2 equaling 1.0 x 10(-3). In addition, the activity of the Cr(III)-grafted TiO2 photocatalyst was highly reproducible. (c) 2010 Elsevier B.V. All rights reserved.