The copper hexacyanoferrate (II) assisted photodegradation of azure B has been examined under visible irradiation (λmax = 640 nm). The azure B is which undergoes degradation on irradiation with visible light. The rate of degradation of azure B was found to follow pseudo-first order reaction. After irradiation for 2 hours, 86% of azure B dye was degraded with addition of 0.05 g / 50 mL copper hexacyanoferrate (II) to solution 1 x 10-5 M of azure B. The influence of pH, semiconductor amount, azure B concentration, and light intensity were investigated and optimum conditions are recorded. The photodegradation was conducted in basic medium and at room temperature.