An amphiphilic pyrrole derivative, 11-pyrrolylundecanoic acid (PUA) was synthesized and the Y-type multilayer Langmuir-Blodgett (LB) film was successfully fabricated by the conventional vertical dipping method. However, it was not possible to fabricate an elcetroconductive polymeric LB film from PUA. Well-ordered electroconductive Y-type poly(thiophene-co-PUA) LB film was successfully prepared by in situ copolymerization of thiophene and PUA at air-water interface by spreading the chloroform solution of thiophene and PUA with various feed ratio onto a subphase containing FeCl3. The optimum condition for the preparation of poly(thiophene-co-PUA) LB film was at 17 degrees C and pH 5.3 under the surface pressure of 40 mN/m(2) with the feed mole ratio of 10: 1 (thiophene/PUA). Poly(thiophene-co-PUA) LB multilayer film showed electrical conductivity of 7.15 x 10(-5) S/cm and very smooth surface. (c) 2005 Elsevier B.V. All rights reserved.