The electric field induced dipole model which is useful for interpreting the mechanism of photogenerated charge transfer in nano-TiO2 has been introduced using photovoltage electric field scanning technique. Based on above model, we suppose that diffusion mechanism controls the photogenerated charge transfer in nano-TiO2. Also, we have studied the behavior of charge transfer in nano-TiO2 under external electric field and found that the photogenerated charge transfer is controlled by different transfer mechanisms under different applied external electric field. (c) 2005 Elsevier B.V. All rights reserved.