The influence of temperature and thickness on the electrical transport properties of 10% excess tin-doped polycrystalline SnTe thin films were investigated. From the observed variation of electrical resistivity and Seebeck coefficient it is concluded that the material exhibits a p-type degenerate behaviour. Using the size effect data, different physical parameters such as Fermi energy, effective mass and scattering parameter were evaluated and compared with the results on SnTe thin films to understand the effect of excess tin. © 1988 Chapman and Hall Ltd.