Thin films from the Ge-Se-B system have been prepared by vacuum evaporation. The structure and the composition of the films have been investigated using electron microscopy and Auger electron spectroscopy, respectively. The d.c, conductivity of thin-film Al-(GeSe5)(1-x)B-x- Al (0 < x < 20 at.%) samples has been measured at values of the applied electric fields up to 10(9) V/m at room temperature. From the current-voltage characteristics the values of the work function of the electron at the Al-GeSeB interface, chi = 0.85 eV, the relative dielectric permittivity of the layer, epsilon = 6.72, and the effective electron mass in the conduction band, m(c)/m = 0.29-0.98 have been derived. The experimental results are in a good agreement with Christov's theory for injected electron currents in the insulators.