Manganese silicate, a stable and efficient catalyst prepared in the laboratory has been successfully used as a catalyst combined with ozonation in the degradation of m-Chloronitrobenzene (mCNB). The catalytic ozonation removal effectiveness of mCNB was investigated under various physicochemical conditions. Both the adsorption and the single ozonation were not effective for the degradation of mCNB, but the presence of manganese silicate in ozonation process could substantially enhance the mCNB removal efficiency. The hydroxyl radical scavenger experiment confirmed that manganese silicate catalytic ozonation followed a radical - type mechanism. The increasing of the manganese silicate dosage could enhance the removal effectiveness of mCNB. The manganese silicate catalyst could be recycled easily without decreasing any ozone catalytic activity after four successive reuses. It is concluded that the manganese silicate was an efficient green catalyst for mCNB degradation in drinking water.