Metal-free octacyanophthalocyanine (H2PcOC), one of the strongest organic acceptors with fair stability and electric conductivity, was examined as the cathode-active material of a lithium battery composed of (metallic lithium/electrolyte solution/H2PcOC). The capacity and energy density based on the quantity of cathode-active material were 137 mA h g−1 and 222 W h kg−1 at 1 V cutoff, respectively. The cycle life of this battery exceeded 20 at the discharge depth of three electron reduction (112 mA h g−1) per H2PcOC unit. It was found that H2PcOC is a promising candidate as the cathode-active material for lithium secondary batteries.