Langmuir films formed of derivatives of 4-aminonaphthalimide and their binary mixtures with the liquid crystal 4-heptyl-4'-cyanobiphenyl (7CB) have been studied. The films have been characterized by the surface pressure-area (-A) and surface potential-area (V-A) isotherms and by Brewster angle microscopy (BAM). Additionally, the electronic absorption spectra of a monolayer on the water surface at different stages of the film formation were recorded. On the basis of these spectra the conclusions about the ability of the dye molecules to form self-aggregates at the air-water interface have been drawn.