Advanced oxidation of an azo dye, Basic Blue 9 (BB9) by Fenton oxidation was investigated in batch experiments. The UV-vis spectral changes of in aqueous solution during Fenton process were studied. It was easier to destruct the azo linkage group than to destruct the aromatic rings of (BB9) by Fenton process. The effects of different reaction parameters such as initial ferrous concentration, initial hydrogen peroxide (H2O2) concentration, initial pH, the initial (BB9) concentration and the temperature on the oxidative degradation of (BB9) have been assessed. The optimal reacting conditions for the color and COD removal were determined and it was found to be initial pH = 3.0, H2O2 = 100 mgL(-1), Fe2+ = 3 mgL(-1) at 20 degrees C temperature for 100 mgL(-1) initial dye concentration. pH is highly effective parameter of color and COD removal in this work. Under optimal conditions, 100% color and 91% COD efficiencies of dye in aqueous solution were achieved within 20 min reaction time. The color removal kinetic of azo dye, (BB9), has also been investigated in the different H2O2 concentration. Kinetic data were studied using Behnajady-Modirshahla-Ghanbery model for color removal. It has been found that experimental kinetic data are represented well by Behnajady-Modirshahla-Ghanbery kinetic.