The electrochemical properties of polyesters derived from oligothiophenes have been studied in solution, and as Langmuir-Blodgett (LB) and cast films. Polyesters with four or five thiophene units exhibited a well-defined voltammetric response and good LB transfer characteristics. Mono and multilayer LB films were electroactive with clear symmetrical peaks, better developed than for the cast films. These films can be p- or n-doped electrochemically.