Thin films of nanocrystalline CdS were obtained at the water-toluene interface by reacting cadmium diethyldithiocarbamate in toluene with aq. Na2S. Three parameters unique to the topical deposition scheme: the effect of column heights, stirring and the action of molecular surfactants are systematically investigated. The obtained nanocrystalline aggregates are characterized by scanning- and transmission electron microscopy, X-ray diffraction and profilometric measurements. Conditions for obtaining smooth device quality thin films have been identified during these experiments.