The radionuclide ¹³⁹Ce is widely used as a component of calibration multisources. In our laboratory preparation of high purity carrier-free ¹³⁹Ce was worked out. The thick target yield of ¹³⁹Ce produced bombardment of ¹³⁹La with 13 MeV deuterons was found to be 159 kBq/mAh. The product ¹³⁹Ce was separated from macroquantities of lanthanum by extraction with diethyl ether (DEE) in the system DEE-HNO₃. The optimum conditions of ¹³⁹Ce isolation were determined.