The electrophysical properties in air and in the atmosphere with ammonia vapor content of nanosized films of ZnO and SnO2 structured in the process of production using polymers were studied. The investigated electrophysical properties of those films in air and in an atmosphere containing ammonia vapors showed the presence of significant changes in the conductivity of both types of films. The nature of these changes is somewhat different. In ammonia vapors, the current in a zinc oxide film is many times greater than in air. And the tin oxide film in ammonia vapor becomes more high-resistant in comparison with its resistance in air. It was found that the conductivity of both types of films is controlled by intercrystalline potential barriers. However, upon contact with ammonia vapors, these barriers decrease in the zinc oxide films, while the opposite process is observed in the tin dioxide film. The reversible nature of the processes of ammonia molecules interaction with oxide films is observed in both cases. Both for ZnO and for SnO2 the sensitivity to ammonia is recorded already at room temperature. It was also established that the initial characteristics of both types of films were quickly restored without additional measures. These facts make the studied nanostructured films of ZnO and SnO2 using polymers to be promising material for sensitive elements for ammonia gas sensors.