The advantages of high energy cyclotrons as compared to small compact cyclotrons for the production of special radionuclides
are outlined. The routine production of123I (T=13.3 h) and28Mg (T=21.1 h) by means of high energy nuclear reactions at the Jülich Isochronous Cyclotron is described. The reaction127I(d,6n)123
123I at 78 to 64 MeV is used for the production of123I with thick target yields of 8 mCi/μAh and high radionuclidic purity. The practical experience in the application of this
process, which is well suited for the production of Na123I and for123Xe-exposure labelling techniques, is reported.28Mg is produced by the27Al(α, 3p)28Mg reaction at Eα=140 to 30 MeV with thick target yields of 40 μCi/μAh. The carrier-free28Mg is separated from the matrix activities by coprecipitation and anion exchange with chemical yields of 80%.