The electrochemical behavior of a soluble polyimide (Tani-polyimide) derived from an aniline trimer was investigated, Similar to processes observed in polyaniline, two typical redox processes involving protonation and ion insertion were observed. Due to the presence of an isolated, short quinonediimine or N,N'-diphenyl-p-phenylenediamine segment, Tani-polyimide displayed an electroactivity at higher potentials and did not undergo an electrochemical degradation reaction.