Electrochemical copolymerization of diphenylamine (DPA) with anthranilic acid (AA) was performed in aqueous 4 M H2SO4 solution for different feed ratios of DPA using cyclic voltammetry. The copolymer film was grown for different numbers of cycles, C-n, and feed ratios of DPA. Electrochemical homopolymerization of DPA was also carried out under identical conditions and compared. A growth equation of the deposited films in terms of concentrations of DPA and AA and C-n is deduced as Q(G) = k[DPA](2.0)[AA]C--0.2(n)1.2 by utilizing the charge associated for film deposition. The copolymer compositions were determined by X-ray photoelectron spectroscopy. Reactivity ratios of DPA and AA were computed by using Fineman-Ross and Kelen-Tudos methods.