The N-sulphopropyl-substituted thiatricarbocyanine dyes can be incorporated into composite monolayers with hexadecylamine (HDA) at the air-water interface. The composite monolayers including the dyes can be transferred onto a solid substrate. The spectroscopic properties of Langmuir-Blodgett (LB) films were investigated by optical spectroscopy. The J-aggregate formation was first observed for three tricarbocyanine dyes. The J-aggregate structure depends on the dye concentration in the mixture with HDA as well as on the constant pressure value at which the transfer onto quartz slides is performed. LB films with a molar ratio of dye to HDA of 1:10, transferred at 30 mN m(-1) show the greatest shift of the J-band from the monomeric one.