Background: Due to their polycyclic and toxic structure, dyes have a high ability in causing adverse acute and chronic effects on human exposed to them. In present study, the decolorization of acid green3 from aqueous solution by UV/ H₂O₂ method was investigated
Methods: This is an applied-experimental study. Parameters of pH in the amount of 3,7 and 11, contact time in 5,15, 30, 45 and 60 min, dose of H₂O₂ in 10, 30 and 50 mg/l and initial concentration of acid green3 in 50, 100 and 150 mg/l were examined to reveal the optimum amounts of these parameters. In order to emit the UV radiation, photo reactor with a 2-lit volume was applied, also to measure remaining concentration of dye, spectrophotometer device, model DR 5000 was employed. Chemical oxygen demand (COD) test based on 5220C method (standard method book) was used for determining amount of oxidation.
Results: Results showed that contact time = 60 min, pH=7, acid green concentration=50 mg/l and dose of H₂O₂ =30 mg/l are optimum condition at which the removal amounts of dye and COD were obtained about 97 and 85%, respectively. 
Conclusion: In the study, it is observed that parameters of contact time, pH, initial concentration of dye, and dose of H₂O₂ have a significant influence on the removal of the dye by UV/H₂O₂ process. Due to acceptable results of UV/H₂O₂ in the oxidation of the dye and the reduction of COD, this method can be introduced as reliable process to remove of acid green 3 from industrial wastewaters.