An advanced oxidation study using Fenton's reagent, i.e., ferrous sulfate and hydrogen peroxide was carried out for studying oxidation of eosin dye. Effects of concentration of various reagents on the degradation of dye were explored during an advanced oxidation process. It was found that ferrous concentration plays a major role in dye decomposition. Rate of dye decomposition is faster with an increase in ferrous sulfate concentration compared to the increase in hydrogen peroxide concentration. A detailed kinetic model was proposed. Profiles for eosin, hydrogen peroxide and various intermediates were also generated. The rate constant of the reaction of eosin with a hydroxyl radical was found to be of the order of 109 l/mol.s.