A highly ordered multilayer film was formed by casting the aqueous dispersion of an ethylenediamine-containing double-chain amphiphile 1. Dipping of the cast film in aqueous cadmium halides led to incorporation of specific amounts of CdCl2 or CdBr2 without losing the regular multibilayer structure, as confirmed by differential scanning calorimetry and reflection X-ray diffraction. Elemental composition determined by X-ray photoelectron spectroscopy and Cd-113 MAS -NMR spectroscopy indicated the presence of tetrahedral structures of CdCl42- and CdBr3- species coordinated by amphiphile 1. Upon exposure of the 1(2)-CdCl4 composite film to H2S gas at room temperature, Q-state CdS particles (size, similar to 30 Angstrom A) were formed. In the case of the 1-CdBr3 composite film, one sulfur atom was introduced per four Cd2+ ions without substantial changes in the coordination structure. This indicates that a novel Cd-Br-S cluster was formed in the interbilayer space of preorganized amphiphilic ligands. The multibilayer cast film serves as a molecular template for controlled synthesis of novel organic/inorganic superlattices.