The mixed Langmuir-Blodgett (LB) films of polyaniline and stearic acid were successfully prepared. They formed stable monolayers at the air-water interface and could be deposited onto solid substrates as Y-type films using a usual LB technique. The stearic acid was removed from the LB films by either immersing the films in organic solvents or heating the films under reduced pressure. The replica method coupled with transmission electron microscopy (TEM) confirmed that these treatments were useful for the preparation of smooth films. The spectroscopic measurements proved perfect removal of the stearic acid after the treatment in solvent. Different electrochemical properties were observed for two kinds of the LB films by cyclic voltammetry. This method made it possible to prepare LB films consisting of polyaniline alone, whose thickness is only 6 A per layer.