Abstract UV and visible light was used for exciting electron transitions between different energy states on the surface of polycrystalline n-TiO 2 electrodes in 1M H 2SO 4 electrotyle. By systematic variation of wave length and bias voltage, we were able to distinguish a dual-step exciting process (band-surface states-band) from ordinary band-band transitions with subband gap illumimation. Two current spikes in response to light on and off were explained as the transient rush of electrons from surface states to the conduction band and vice versa. And the surface states were estimated to be around 1.8 eV above the edge of the valence band. Thus, a simple method for observing the elementary steps directly in photoexcited charge transfer via surface states on TiO 2 has been proposed.