Background & objectives: Anthraquinone dyes such as reactive blue 19 in water resources and industrial wastewater effluents are important environmental challenges in many countries. Various methods including photo-catalytic oxidation have been considered to remove these dyes. Methods: This research was carried out in laboratory scale using a 500 ml batch photoreactor. The effects of operating parameters such as concentration of catalyst, pH, initial dye concentrations, and reaction time on removal of reactive blue 19 were evaluated. Response surface methodology based on Central Composite Design was used to assess the effects of independent variables on removal efficiency and prediction of the best response value. TiO2 nano-fiber photo-catalytic oxidation experiments were done and repeated three times using the optimum condition obtained for each variable. The initial and final dye concentrations were determined by a spectrophotometer. Results: The effect of pH, concentration of nano-particles, and detention time was significant on the dye removal efficiency. The effects of pH and nano-particle concentration on the dye removal efficiency were linear. Dye removal efficiency was also correlated to square of nano-particle concentrations. The optimum photo-catalytic oxidation removal efficiency of 95% was occurred at 1 mg/lit of TiO2 nano-particle, 20 mg/lit of initial dye concentration, pH = 4.2 and the detention time of 75 min. Conclusion: The results showed that the applied method in this study is efficiently able to remove and destroy the dye. At the same condition, the removal efficiency of TiO2 nano-particle was higher than the TiO2 nano-fiber.