Langmuir-Blodgett films modified by an electrochemically active compound, such as cobalt hexacyanoferrate, are of interest to create water-insoluble film electrodes with a high concentration of active centers and a low response time. The possibility of introducing cobalt hexacyanoferrate nanoparticles stabilized by sodium hexametaphosphate in octadecylamine monolayers with subsequent transfer them to a solid substrate by the Langmuir-Blodgett method is shown. Cobalt hexacyanoferrate nanoparticles were obtained by gradual mixing of an equimolar reagents mixture with the addition of sodium hexametaphosphate as a stabilizer. The size of nanoparticles were determined by the laser diffraction method, the size of their main number was about 12 nm. The hydrosol of the nanoparticles stability was studied photometrically in the pH range 2-4. The pi-A octadecylamine monolayers isotherms on a subphase containing cobalt hexacyanoferrate nanoparticles were studied at the same pH values. According to the obtained data, optimal conditions for the monolayers transfer to a solid substrate by the Langmuir-Blodgett method were chosen. The morphology of the resulting films was studied on the surface of solid substrates. The electrochemical properties of electrodes based on Langmuir-Blodgett films in various solutions of electrolytes were studied by using the cyclic voltammetry and potentiometry.