Abstract: In this paper, the electrocatalytic performance and formic acid tolerance ability of the Vulcan XC-72 carbon black supported Ir (Ir/XC) catalyst and the macropore carbon supported Ir (Ir/MC) catalyst in the direct formic acid fuel cell were investigated using the energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy and electrochemical technique. It was found that the electrocatalytic performance of the Ir/MC catalyst for the oxygen reduction is better than that of the Ir/XC catalyst. The onset reduction potential of oxygen at the Ir/MC catalyst is 0.1 V more positive than that at the Ir/XC catalyst. The limiting current density of the oxygen reduction at the Ir/C catalyst is 30% larger than that at the Ir/XC catalyst. This could be only attributed to the large pore diameter and porosity as well as high graphitization extent because the average diameters and relative crystallinity of two catalysts are similar. In addition, both catalysts have the good formic acid tolerance. Therefore, MC is a carbon carrier of the catalyst better than XC.