The structural, morphological, and chemical properties of the β-Ga₂O₃-GaS structure are investigated by means of X-ray diffraction technique, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. By selecting the annealing temperature and the duration of the annealing process, one can obtain the β-Ga₂O₃ nanostructured compound, such as nanowires and nanoribbons, with thicknesses and surface areas required for certain types of electronic devices, in particular, for the gas and humidity sensors with various applications. Photosensitive wavelength range is from 200 to 320 nm. The results show that the photosensitivity and electrical conductivity of the n-type β-gallium oxide nanostructured layers on a GaS substrate, such as the dependence of the current intensity in the circuit of β-Ga₂O₃-GaS structure on the air relative humidity in the range from 42 to 92%, make this structure highly attractive for sensing applications. Reported data are important for the development of humidity sensors for harsh environments.