In order to study the effect of the type of light source on the degradation efficiency, sunlight (intensity: 8.425 ื 1015 quanta/s), UV light (intensity: 2.3775 ื 1015 quanta/s) and mercury vapor lamp (300 W, intensity: 3.31 ื 1015 quanta/s) illumination were considered. It was observed that the degradation of acid violet was rapid under sunlight illumination, when compared to UV and mercury