This effort is to improve CuO's chemical-looping characteristics by introducing iron ore, chrysolite and limestone to obtain high power efficiency in chemical looping combustion (CLC) power plants. The reactivity and oxygen uncoupling behavior were evaluated by thermogravimetric analysis (TGA) in N-2 and CO2 atmosphere under different heating rate. CuO modified by chrysolite and limestone showed better performance than iron ore-added CuO oxygen carrier (OC) in a CLC system. CO2 could play an important role in the gasification of char only when the temperature is above 800 degrees C. Two peaks were found in the Differential thermal gravity (DTG) curve when modified CuO reacted with char. That could be the solid-solid reaction turned into gas-solid reaction with temperature increasing. Scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) technique analysis indicated an enhancement of high temperature tolerance of Cu-based OCs, while CuO occurred sever sinter and agglomeration. Higher temperature tolerance means higher temperature off-gas from the fuel reactor entering the heat utilization power generation system, which could obtain higher efficiency in CLC power plants. (C) 2020 Elsevier Ltd. All rights reserved.