Electrically conducting arachidic acid/polypyrrole (PPy) composite films were prepared by exposing the arachidic acid LB films containing ferric chloride to pyrrole vapor. The optimum conditions to deposit matrix LB film were the subphase temperature of 23-25 degrees C, pH of 6.0 and ferric chloride concentration of 5.0 X 10(-5) M. The formation of PPy in the arachidic acid matrix LB films was confirmed by UV-visible spectra, FTIR spectra, and scanning electron micrographs. The average thickness of the composite LB films prepared at 0 degrees C was 1525 Angstrom. The composite films prepared at lower temperatures have more uniform surface and exhibit higher electrical conductivity than the films prepared at higher temperatures do. The in-plain conductivity and the transverse conductivity of the composite film were 10(-3)-10(-2) S/cm and 10(-6) S/cm, respectively, and, thus, the conductivity anisotropy was about 10(3).