The mechanistic study of iridium (III)-catalyzed oxidation of paracetamol has been studied by sodium N-chloro-p-toluenesulfonamide (chloramine-T) in aqueous perchloric acid medium at 308 K. The reaction followed first-order kinetics with respect to [chloramine-T], [paracetamol] and [Cl-] in their lower concentrations range, tending to zero-order at their higher concentrations. First-order kinetics with respect to [Ir(III)] was observed for the oxidation of paracetamol. The rate of reaction decreased with increasing [H+] and [p-toluene sulphonamide, PTS] were observed for the oxidation of paracetamol. The variation of the ionic strength of the medium had no significant effect on the rate of the reaction. The first-order rate constant increased with decrease in the dielectric constant of the medium. The values of rate constants observed at five different temperatures were utilized to calculate the activation parameters. The reaction between chloramine-T and paracetamol in acid medium exhibits 1:2 stoichiometry. A plausible mechanism from the results of kinetic studies, reaction stoichiometry and product analysis has been proposed. (C) 2009 Published by Elsevier B.V.