Acid Blue 113 dye (AB 113) is a synthetic dye which is resistant to various treatment processes. In this study, Fenton (Fe2+/H2O2) and a Fenton-like (Fe2+/S2O82−) processes were tested for the removal of AB 113 from water. Three different Fe2+ doses were adjusted by the following Dye:Fe2+:H2O2 and Dye:Fe2+:S2O82− molar ratios: 10:1:5; 10:5:5 and 10:10:5. It was observed that under 10:1:5 and 10:5:5 molar ratios, Fenton process resulted with better AB113 removal where 42% and 45% absorbance removal were recorded, respectively. On the other hand, Fe2+:S2O82− process efficiency was 13% and 38%, under these doses. When the molar ratio 10:10:5 was used, both processes ended up with similar maximum removal which was 69%. Increasing oxidant concentration (molar doses of 10:10:10 and 10:10:50) caused no significant removal increase. The degradation curves were best fitted to first order kinetics. Under 10:1:5 molar ratio Fenton process was five times faster (observed reaction rate constant, k = 0.010 min−1) than (Fe2+/S2O82−) process (observed reaction rate constant, k = 0.002 min−1). When the molar ratio has increased the speed of the reactions become almost the same where under 10:10:5 molar ratio it was calculated as 0.15 and 0.13 min−1 for Fe2+/H2O2 and Fe2+/S2O82− processes, respectively.