A new type of Mn-based oxygen carrier was prepared by impregnating manganese ore with copper nitrate solution. Cyclic reduction and oxidation reactivity of the materials was investigated in a fluidized-bed reactor. The potential use of these oxygen carriers for chemical looping combustion (CLC) was examined. The reactivity of the manganese ore can be highly improved by impregnation of copper. The reactivity of the oxygen carrier reduction is higher with a larger amount of copper impregnated. However, the degree of the reactivity enhancement is not proportional to the amount of copper doped on the oxygen carriers. An important finding is that, even with low Cu loading, such as 0.5 wt % copper impregnated on manganese, the period with full CO conversion can be enhanced 6 times. A very interesting phenomenon is that the Cu-modified manganese ore can completely convert CO, even at a low temperature, such as 500 degrees C. This study proves that the reactivity of the manganese ore could be significantly improved by impregnating copper, even with a small amount. The copper impregnation method could be very promising to improve the reactivity of the manganese ore as oxygen carriers for CLC.