Thin ZnS_xSe_1-x films on glass substrates have been obtained by thermal evaporation. Electrodes from In or other materials have been deposited on thin films, and the temperature dependence of electrical conductivity was investigated during a series of successive cycles of heating and cooling performed at a rate of 6 K/min in a temperature interval from 300 K to 500 K. The measurements demonstrated that the energy of thermal activation at low temperatures (∆E₂ = 0.13–0.43 eV) is much lower as compared to that measured at high temperatures (∆E₁ = 0.43–1.89 eV). It was found that in both ranges of low and high temperatures the thermal activation energy increases with increasing the sulfur content in thin films. It was demonstrated that at low temperatures the dominant mechanism of electrical conduction is of Mott-type.