Insoluble AgCl and soluble CuCl2 were selected and investigated as model compounds of transition-metal chlorides for electrochemical conversion cathode materials. The experimental results demonstrated that the AgCl nanocrystals can convert reversibly to metallic Ag with nearly full utilization of its one-electron redox capacity (187mAhg−1). Similarly, the CuCl2-filled mesoporous carbon can realize a reversible two-electron transfer reaction, giving a very high reversible capacity of 466mAhg−1 after 20 cycles. These data imply that the metal chlorides can undergo complete electrochemical conversion utilizing their full oxidation states for electrical energy storage as previously reported metal fluorides, possibly being used as high capacity cathode materials for Li-ion batteries.