Langmuir-Blodgett films containing complex ions of platinum(II), platinum(IV) and palladium(II) were prepared from compressed monolayers of dimethyldioctadecylammonium bromide on subphases of these ions. The films were characterized by measuring the surface pressure vs. area per molecule (π/A) isotherms and by UV/visible spectroscopy, grazing angle FTIR spectroscopy and X-ray photoelectron spectroscopy. The reactions of these films with H 2 S and hydrazine were investigated by the above spectroscopic techniques and by atomic force microscopy (AFM). The absorbance onsets of the H 2 S-exposed films are dramatically blue shifted relative to the bulk bandgaps of PtS 2 , PtS and PdS. This is consistent with the formation of particles in the Q state size regime. AFM images of hydrazine-treated (DDA) 2 (PdCl 4 ) films on mica revealed metal particles with an average diameter of 3.6 nm.