Mesoporous MCM-41 and Fe loaded MCM-41 (Fe/MCM-41), which were prepared by hydrothermal and dipping method respectively, were applied as heterogeneous catalysts for the ozonation of p-chlorobenzoic acid (p-CBA) in aqueous solution. MCM-41 and Fe/MCM-41 were characterized by low and wide angle XRD, atomic absorption spectrometer (AAS) and N-2 adsorption-desorption techniques. Due to the synergetic effect, Fe/MCM-41/O-3 process significantly improves p-CBA and total organic carbon (TOC) removal efficiency compared to ozonation alone. Under the experimental condition, TOC removal efficiency of Fe/MCM-41/O-3 process is over 94.5% at 60 min oxidation time, only 61.5% by MCM-41/O-3 process, 62.3% by O-3 alone process. Fe/MCM-41/O-3 process follows apparent first-order kinetics, while ozonation alone. MCM-41/O-3 and Fe2O3/O-3 processes follow apparent second-order kinetics. The presence of tert-butanol (TBA) in the Fe/MCM-41/O-3 process indicated that the oxidation mechanism of p-CBA occurs via (OH)-O-center dot in the liquid bulk. Fe/MCM-41 is a promising catalyst for the ozonation process of p-CBA. (C) 2011 Elsevier B.V. All rights reserved.