Novel ultrathin unit layers and built-up multilayers of polymeric imine are obtained when a spreadable polyfunctional aldehyde or its precursor, particularly the alkyl Schiff base formed by its condensation with an alkyl amine, is spread on the surface of an aqueous subphase containing a diamine. The resulting polymeric imine unit layers can be transferred and built up on substrates which included quartz, aluminum and chrome-plated glass, and semiconductors.