The thermally induced depolarization and Verdet constant of CeF3 crystals-their most important characteristics-have been studied in the 79-293 K temperature range. It has been found that thermal effects reduce substantially upon cooling down to 79 K and the Verdet constant grows in inverse proportion to the temperature. It was shown that CeF3 crystals are not inferior to TGG as a medium for Faraday isolators, including cryogenic ones.