The kinetics of oxidative decolorization of acid orange 8 (AO8) by chloramine-T and bromamine-T in HClO 4 medium has been investigated spectrophotometrically (λ max = 490 nm) at 298 K. Kinetic runs were executed under pretend first-order conditions of [oxidant] o >> [AO8] o. Under identical experimental conditions, reactions with both the oxidants follow identical kinetics with a first-order dependence on each [oxidant] o and [AO8] and a fractional-order dependence on [HClO 4 ]. Stoichiometry of the reaction was found to be 1:1 and the oxidation products were identified. The reaction was studied at dissimilar temperatures and activation parameters have been computed. Effects of p-toluenesulfonamide, halide ions, ionic strength and dielectric constant of the medium have been investigated. Reaction mixture fails to induce polymerization of acrylonitrile. The rate of oxidation of AO8 is about twofold faster with BAT as compared to CAT. This may be endorsed to the diversity in electrophilicities of Cl + and Br + ions and also the van der Waal's radii of chlorine and bromine. Authentic mechanism and associated rate law have been deliberated for the observed kinetics.