Langmuir-Blodgett (LB) films have been built up from a novel amphiphilic derivative of a benzothiazolium styryl dye containing a 18-crown-6 ether group. Aggregates of the chromoionophore were found to form when the LB film was immersed in acidic water. This process took a few hours, probably because of the restricted orientational movement of molecules in the film. Complex formation with K+, Ag+, Pb2+, and Ba2+ metal ions has been studied for bilayer films immersed in acidic solutions. These processes are fully reversible.