Abstract: In present study the photocatalytic degradation of commercial azo dye Direct Red 5B (DR5B dye) has been carried out in presence of recently developed photocatalyst: methylene Blue immobilized resin Dowex-11, under visible light. The effect of process parameters such as variation of the dye concentration, pH, light intensity and amount of catalyst loading on the reaction rate has been studied .The rate constant has an optimal conditions at 30 oC , pH 7.5,2.0gm/L catalyst loading, light intensity 200 watt & 40mg/L concentration of the dye. Kinetic study of photo degradation follows pseudo first order kinetics. A Tentative mechanism of the photocatalytic degradation of DR5B dye has also been proposed.