Isophthalic acid produced from the oxidation of m-xylene by air is catalyzed by H 3 PW 12 O 40 (HPW) loaded on carbon and cobalt. In this paper, acetic acid solution is used to treat the carbon to ameliorate the catalytic ability of HPW@C catalyst. The experiments indicate that the best supporter is obtained by immersing the carbon in 3.5 mol L −1 HOAc for 24 h followed by carbonized at 500 °C for 4 h. The surface characterization proves that the modification with HOAc augments acidic groups and amplifies specific surface area on the carbon surface. The surface chemistry plays a more vital role than the physical properties in determining the catalytic ability of HPW@C. We find that 76.7% more IPA is produced after 180 min reaction by the HPW@C made of the carbon modified in the best conditions than by the HPW@C made of the original carbon.