In the present work, nanoparticles of pure TiO2 and manganese doped TiO2 were prepared by sol-gel method. As-prepared photocatalyst performance was evaluated by degradation of rose Bengal in synthetic waste water system under visible light. The degradation of dye was studied spectrophotometrically. Optimum conditions were achieved for degradation of dye by varying different rate affecting parameters like pH, concentration of dye, amount of photocatalyst, and light intensity and these were found to be 7.0, 0.90 × 10−5 M, 0.12 g, and 60.0 mWcm-2, respectively. The physicochemical properties of samples were characterized by XRD and SEM. The observations revealed that Mn doped TiO2 showed better photocatalytic performance than pure TiO2.