Abstract: In this paper is described a procedure for the preparation of 109Cd X-ray source.The 108Cd is obtained by irradiating silver target in a 1.5m cyclotron according to the nuclear reaction 109Ag (d ,2n)109Cd. Silver is quantitatively separated from cadmium by elutio.n with 6.9N HBr from a column of 717 anion exchange resin in the bromide form with arecovery of≥98%·The source is prepared from the obtained 109Cd using the molecular plating method and satisfactorily meets the needs of water-oil densimeter for the oil industry.