© 2017 The Royal Society of Chemistry. The complete reaction mechanism of H 2 S desulfurization on anatase TiO 2 (001) surface was elucidated using the plane-wave based density functional theory (DFT) method. The reaction starts from the dissociative adsorption of H 2 S on the TiO 2 surface. Subsequently, two competitive routes, H 2 O and H 2 formation, were investigated. The activation barriers for H 2 O formation range from 11 to 13 kcal mol -1 , whereas those for H 2 formation are extremely high in the range of 67-87 kcal mol -1 . On the basis of the activation energy barriers, the results indicate that the anatase TiO 2 (001) is very active for H 2 S desulfurization to produce H 2 O, resulting in S-substitution at the O 2c sites on the TiO 2 (001) surface. Electronic charge analyses indicate that S-doping onto the TiO 2 surface can enhance the photocatalytic activity of TiO 2 by reducing its band gap. In addition, by comparison with other metal oxide catalysts, such as TiO 2 (101), CeO 2 (111), CeO 2 (101), ZnO (1010) and α-Fe 2 O 3 (0001), we found that TiO 2 (001) is the most promising catalyst for H 2 S desulfurization.