Abstract <p>An expression for the electrical conductivity of a thin polycrystalline film is obtained. To solve the problem, a kinetic equation is used in the relaxation time approximation, taking into account the scattering of electrons at the boundaries of the grains of the polycrystalline film. The influence of surface scattering of charge carriers is described by the Fuchs diffuse-specular boundary conditions. The limiting cases of degenerate and nondegenerate electron gas are considered. The dependence of electrical conductivity on the scattering intensity at the grain boundary and on the length of the electromagnetic wave inside the film is analyzed. The obtained results are compared with the well-known experimental data for the silicon layer.</p>