AbstractThe size dependence of the transport coefficients of semi‐metals has been studied assuming nonspherical energy surfaces and taking into account the energy dependence of the relaxation time. Detailed calculations have been performed for thin bismuth films at low temperatures considering the anisotropy in the mass tensor. Cartesian tensor expansion technique has been used to solve the Boltzmann transfer equation in the presence of a static electric field applied along the surface of the film and a magnetic field in the transverse direction. Results obtained are in good qualitative agreement with the experimental results of Colombani and Huet.