Isophthalic acid (IPA) is usually produced by the Co-Mn-Br catalyst system. In this study, a bromine-free catalyst system consisting of H-3 PW12O40/CO(OAc)(2)/Mn(OAc)(2) has been put forward to oxidizing m-xylene (MX) to IPA. The experimental results proves that the homogeneous H3PW12O40/Co(OAc)(2)/Mn(OAc)(2) catalytic system is able to catalyze the oxidation of MX to IPA. The optimal phosphotungstic acid concentration is 0.52 wt%. The optimum Co(II) concentration for IPA production is between 0.044% and 0.088 wt%. The best Mn/Co ratio is found to be 2.46. Temperature has a strong effect on the reaction rates. Oxygen partial pressure influences on the IPA yield greatly. The kinetic parameters such as activation energies, reaction orders have been estimated. (C) 2011 Elsevier B.V. All rights reserved.