Nitrogen doped mesoporous TiO(2) was prepared via a modified two-step hydrothermal route. In contrast to undoped mesoporous TiO(2), nitrogen doped mesoporous TiO(2) has superior photocatalytic activity under both UV and visible light irradiation. Photoluminescence spectra reveal that nitrogen doped mesoporous TiO(2) possesses abundant surface states, which can play a vital role in trapping photoinduced carriers as evidenced by photoelectrochemical process and prolonging the lifetime of the carriers. The remarkably enhanced photocatalytic activity in nitrogen doped mesoporous TiO(2) is attributed to the generated abundant surface states.