Electrical properties of Se‐ and Zn‐doped polycrystalline GaAs deposited by metalorganic chemical vapor deposition on substrates of polycrystalline alumina and glass were investigated. Hall‐effect and resistivity measurements were made over a wide range of temperature (77–420 K). The electrical activation energies were found by measuring the variation of resistivity and carrier mobility of the polycrystalline GaAs films with sample temperature. The resistivity and mobility were found to be temperature activated over a wide temperature range as exp(Eb/kT) and exp(−Eb/kT), respectively, with the same activation energy applying to both properties. The results have been interpreted in terms of a modified grain boundary trapping model.