Thin nanocomposite films based on tin dioxide with a low content of zinc oxide (0.5–5mol.%) were obtained by the sol–gel method. The synthesized films are 300–600nm thick and contains pore sizes of 19–29nm. The resulting ZnO–SnO₂ films were comprehensively studied by atomic force and Kelvin probe force microscopy, X-ray diffraction, scanning electron microscopy, and high-resolution X-ray photoelectron spectroscopy spectra. The photoconductivity parameters on exposure to light with a wavelength of 470nm were also studied. The study of the photosensitivity kinetics of ZnO–SnO₂ films showed that the film with the Zn:Sn ratio equal to 0.5:99.5 has the minimum value of the charge carrier generation time constant. Measurements of the activation energy of the conductivity, potential barrier, and surface potential of ZnO–SnO₂ films showed that these parameters have maxima at ZnO concentrations of 0.5mol.% and 1mol.%. Films with 1mol.% ZnO exhibit high response values when exposed to 5–50ppm of nitrogen dioxide at operating temperatures of 200∘C and 250∘C.