hi this work, direct insertion probe pyrolysis mass spectrometry technique was applied to investigate the thermal and structural characteristics of electrochemically prepared polyaniline (PANI), polypyrrole (PPy), and their composites/copolymers synthesized either by electrochemical polymerization of pyrrole on PANI-coated electrode (PANI/PPy) or by coating PANI on PPy (PPy/PANI) in H2SO4 solutions. It has been determined that the polymer first coated on the electrode degraded to a certain extent during the polymerization of the second. The extent of degradation was greater for PPy and increased with the increase in acid concentration. On the other hand, the detection of mixed dimers confirmed copolymer formation. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 3130-3136, 2009