The photocatalytic bleaching of textile azo dye Reactive Yellow 86 has been carried out in the presence of semiconductor TiO2 and the progress of reaction was observed spectrophotometrically.The effect of various operating parameters like pH, concentration of the dye, amount of photocatalyst and nature of photocatalyst on the efficiency of the reaction has been studied. Kinetic analysis of photodegradation reveals that the degradation follows approximately pseudo first order kinetics according to the Longmuir- Hinshelwood model. The optimum conditions for the degradation of Reactive Yellow 86 dye have been found as dye concentration 2x10-5M, pH= 7.5 and 0.25 g/100 ml catalyst dose. The effect of addition of transition metal ions (Fe2+, Cu2+, Mn2+, Zn2+, Co2+, Ag+) on photodegradation efficiency of TiO2 have been investigated. It was observed that trace quantities of all the added metal ions increases the reaction rate to some extent. The increase in the photocatalytic activity may be due to introduction of new trapping sites by incorporation of transition metal ions on semiconductor surface. A tentative mechanism has been proposed.