Isophthalic acid produced from the oxidation of m-xylene by air is catalyzed by H3PW12O40 (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 degrees 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.