The esr and optical spectra of aniline oligomers indicate the formation of radicals in the potential range between the first and second redox waves of cyclic voltammogram. The hyperfine structure of the esr signal indicate the unpair electron is localized on a phenyl group and two adjacent -NH- groups. The difference in conductivity between the polymer and the oligomer may be attributed to the degree of delocalization of the unpair spin.
