N-doped and oxygen-deficient TiO2 photocatalysts were fabricated by a two-step calcination method using dicyandiamide and commercial TiO2 as starting materials.Photocatalytic activity was tested by decomposing gas-phase benzene under visible light irradiation.The nitrogen dopants and oxygen defects in TiO2 played important roles in benzene photodegradation.It was found that the optimum doping dosages of nitrogen and defects (Ti3+/Titotal) were 0.23wt% and 26at%, respectively.After photooxidation for 5h, the benzene conversion rate and CO2 yielded over the as-doped TiO2 were 72% and 190ppmv, respectively, which were much higher than the sum on NH3-treated and H2-treated TiO2.It suggests that the visible-light activity of the modified TiO2 is attributed to a synergistic effect between substitutional N dopants and oxygen defects in TiO2.