The characteristics of aniline and m-aminobenzoic acid (MABA) copolymer (self-doped polyaniline (PANi) (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 1.0M ZnCl2 and 0.5 MNH4Cl 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 146.4Ahkg−1 with a columbic efficiency of 97–100% over at least 200 cycles between 0.8 and 1.6V. The specific energy is 172.8Whkg−1 and the SDPA cathode exhibits good recycleability.