Fe-200 was synthesized through the calcination of iron powder at 200 degrees C for 30 min in air. On the basis of characterization by X-ray diffraction and X-ray photoelectron spectroscopy, Fe-200 had a core-shell structure, in which the surface layer was mainly composed of Fe2O3, with some FeOOH and FeO. and the core retained metallic iron. The kinetics and mechanism of the interfacial electron transfer on Fe-200 were investigated in detail for the photoassisted degradation of organic pollutants with H2O2. Under deoxygenated conditions in the dark, the generation of hydroxyl radicals in aqueous Fe-200 dispersion verified that galvanic cells existed at the interface of Fe-0/iron oxide, indicating the electron transfer from Fe-0 to Fe3+. Furthermore, the effects of hydrogen peroxide and different organic pollutants on the interfacial electron transfer were examined by the change rate of the Fe3+ concentration in the solution. The results indicated that hydrogen peroxide provided a driving force in the electron transfer from Fe2+ to Fe3+. while the degradation of organic pollutants increased the electron transfer at the interface of Fe-0/iron oxide due to their reaction with center dot OH. (C) 2008 Elsevier B.V. All rights reserved.