The degradation of Alizarin Red S (ARS). an anthraquinone dye was investigated by advanced photo Fen toil process Using zero valent metallic iron (ZVMI) powder as the catalyst wit h symmetrical peroxides like hydrogen peroxide (HP)/ammonium persulfate (APS) as the oxidants. APS is proved to be a better oxidant compared to HP as it provides efficient acidic medium which is critical for Fenton process A kinetic/mathematical model was developed based oil the non-linear regression analysis and the validity of the model was tested by comparing the observed experimental values with the theoretically calculated data. The rate equation obtained was found to be a function of iron dosage,oxidant and dye concentration at pH 3 k = 0.2456[Fe](0.21)[APS](0.15)[ARS](-0.76) k = 0.58[Fe](0.12)[HP](0.10)[ARS](-0.86) The degradation pathway was followed by UV-vis spectroscopy and CC-MS techniques Based on the intermediates analyzed. a probable degradation mechanism has been proposed (C) 2009 Elsevier B V All rights reserved.