The possibility of the formation of very thin (approximately 0.4 nm per layer) thermostable Langmuir-Blodgett films of the ladder-type polymers polyheteroarylenes was investigated. The preparation method included (1) attaching fatty acid chains (using stearic acid) to the soluble prepolymer backbone, (2) deposition of these composite molecules onto the solid substrate using a standard dipping technique, and (3) simultaneous desorption of the fatty acid tails and thermocyclization of the prepolymer at elevated temperatures (100-350 degrees C). The structure and optical properties of the system were investigated by X-ray diffraction and absorption spectroscopy as functions of the chemical structure of the prepolymer and the preparation conditions.