Carbon nanotubes are coated with a layer of copper by an electroless plating method. To prepare CuO/carbon nanotubes, Cu/carbon nanotubes are oxidized by heating to 160 degrees C in air for 12 h. The lithium insertion properties of carbon and CuO/carbon nanotubes are tested by an electrochemical method. Carbon nanotubes can reversibly store 700 mA h Li g(-1) carbon, while CuO in CuO/carbon nanotubes can reversibly store 268 mA h Li g(-1) CuO. Li can insert into the CuO lattice at 1.7 to similar to 1.0 V and be released at 2.3 to similar to 2.5 V vs. Li according to CuO + xe + xLi <-> CuOLix.