Langmuir-Blodgett films containing C-60 and cadmium arachidate were prepared and then exposed to hydrogen sulphide gas to generate cadmium sulphide. The CdS is in the form of nano particles, the blue shift in the absorption spectrum allowing particle size to be calculated. The structural and chemical changes in the film were studied by grazing incidence FTIR spectroscopy and X-ray diffraction. The initial cadmium arachidate and fullerene film did not appear to have the alternate bilayer structure that has been reported for pure arachidic acid and C-60. Exposure to H2S also caused some disruption to the film structure with the planes of Cd2+ being drawn into CdS nano-particles.