In this study, we investigated the use of a silica-supported manganese oxide prepared through the impregnation method for the low-temperature (<150 °C) ozone catalytic oxidation (OZCO) of gaseous monochlorobenzene (MCB). Moreover, the effects of various operating parameters including the reaction temperature, ozone concentration, and space velocity (SV) on MCB removal were also evaluated. In the absence of ozone, MCB conversion achieved over 10 wt % MnOx/SiO2 was only 15% at 250 °C; the conversion increased to 90.4% over 10 wt % MnOx/SiO2 when 900 ppm of ozone was added at 120 °C and SV = 300 000 h-1. In the kinetic analysis, the power-rate law feasibly describes the data of MCB oxidation via OZCO reaction. For temperatures lower than 120 °C, the activation energy and frequency factor were 10.5 kJ mol-1 and 8.05 × 102 L1.187 mol-0.187 g-1 s-1, respectively. Furthermore, the economic feasibility analysis conducted by comparing the cost of the OZCO process relative to that of general catalytic oxidation using V2O5-based catalysts indicates that the OZCO process is more cost-effective for the removal of MCB from flue gas.