The characteristics of aniline and m-aminobenzoic acid (MABA) copolymer (self-doped polyaniline (PANT) (SDPA)) are studied in aqueous electrolytes. The SDPA films are deposited on a platinum electrode by means of cyclic voltammetry. The film is employed as a positive electrode (cathode) for a SDPA-Zn secondary battery that contains 1.0 M ZnCl2 and 0.5 M NH4Cl electrolytes at pH = 5. The cells are charged and discharged under constant current. It is found that the maximum capacity of the SDPA-Zn battery is 146.4 Ah kg I with a columbic efficiency of 97-100% over at least 200 cycles between 0.8 and 1.6 V. The specific energy is 172.8 Wh kg(-1) and the SDPA cathode exhibits good recycleability.