Detection and monitoring of gaseous ammonia in the atmosphere and industrial environments is essential in various fields of application, including monitoring of the food freshness. The sensing element of devices are made largely from inorganic substances, including films of toxic and deficient semiconductors. Currently a large variety of devices are available to detect ammonia, but most of them are expensive and complex to manufacture and use, which causes the search of simpler and cheaper

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... d of manufacturing such sensors.The article is devoted to developing of the sensitive elements of devices based on thin films of conducting polymer – polyaniline (PAN), which attracted considerable attention due to the simple synthesis, low cost, sensitivity to various gases at room temperature. The changes in optical properties of PAN films, caused by interaction with molecules of gaseous ammonia, were studied to identify and establish the gas content in the environment. It is shown that the proposed method of forming the gas sensitive films by chemical deposition of PAN on the surface of optically transparent materials (glass, tin oxide, polymethylmethacrylate) provides high sensitivity to ammonia, which is manifested in the shift of the transmittance band and reducing its intensity. Time of adsorption–desorption equilibrium is 30–60 s, confirming the performance of the optical response of obtained films.