The Langmuir-Blodgett (LB) films of conducting poly(p-phenylenevinylene) (PPV) were prepared by thermal treatment (250-degrees-C, 1 Torr) of the LB film of the PPV precursor, amphiphilic poly(p-xylylene-alpha-diethylsulphonium) salt with perfluorononanoate counterion. The formation of the pi-conjugated PPV structure varied with the thermal annealing time and was studied by means of UV spectroscopy. The elimination of the sulphide and fluorinated fatty acid during the thermal treatment was determined quantitatively by X-ray photoelectron spectroscopy. Both results indicated that extension of the pi-conjugated structure could be realized and conversion from the PPV precursor to PPV could be completed within 10 min under these conditions. Furthermore, transmission electron microscopy examination revealed a gradual change in the surface image from heterogeneous to homogeneous during the thermal treatment, which indicated that a smooth surface of the PPV LB film was gradually formed by the thermal conversion.