Langmuir-Blodgett (LB) films containing a mixture of poly(di-n-hexylsilane) (PDHS) and arachidic acid were prepared. The surface pressure-area curves indicate that PDHS is positioned between the lipophilic ends of arachidic acid monolayers in the LB films. The Si backbone of PDHS is present in both the trans-zigzag planar and disordered states in the LB films. The ratio of the two states is dependent on the deposition number and temperature of the water subphase. The phase transition temperature (approximately 25 degrees C) in the floating monolayer is reduced compared with that in the cast bulk film (42 degrees C).