Poly(4-anilino-1-butanesulfonic acid) sodium Salt was synthesized from the electrochemical oxidation of 4-anilino-1-butanesulfonic acid sodium salt, which was readily obtained from aniline and 1,4-butane sultone. The resulting water-soluble polymer has shown much higher redox cyclability than unsubstituted polyaniline, which was demonstrated by an in situ spectroelectrochemical and a cyclic voltammetric study.