The untreated wastewater from the dye industry having high ammoniacal nitrogen and chemical oxygen demand (COD) significantly pollutes the receiving water, such as a river, having major ill implications on the aquatic environment. The present study is undertaken to address this problem. It investigates the effectiveness of Fenton reagent in simultaneous treatment (removal) of ammoniacal nitrogen and COD present in the wastewater by varying the parameters like pH, concentration of Fe 2+ and H 2 O 2 and their molar ratio. The reaction time for all the experiments was kept 60 min. The experimental analysis in terms of calculating the residual % of ammoniacal nitrogen and COD revealed that the maximum reduction occurred at pH 3. At this pH, further set of experiments were performed by varying the molar doses of Fe 2+ /H 2 O 2 as 1:1, 3:3 and 5:5, and the results reveal that the maximum reduction in both ammoniacal nitrogen and COD happens at molar dose of 3:3. To understand the effect of the concentration of Fe 2+ and H 2 O 2 on the respective removal efficiency, set of experiments were performed by taking the molar ratio of Fe 2+ /H 2 O 2 as 2:1, 3:1, 5:1, 1:2, 1:3 and 1:5. The experimental analysis reveals that the maximum reduction happened at molar ratio 1:3. Fenton process can mineralize the pollutants up to 75.8% and 78.6% for ammoniacal nitrogen and COD removal. The findings of the study would be of great use for planning and optimizing the wastewater treatment facility for the dye intermediate industry.