Abstract: 233Ac is produced via 238U (3He, 8B) or equivalent nuclear reactions using the Brookhaven 60-in. isochronous cyclotron, giving a β half life of > 120 sec and production cross section 1-2 μb. We also unambiguously identified 233Ac produced by irradiating 238U targets with 28 GeV protons at the Brook-haven Alternating Gradient Synchrotron (AGS), and the half-life of 233Ac after separated from Th is found to be 2.3+0.3 min. and the production cross section is 100μb.We have also measured the production cross sections for 233Th and 231Th from the bombardment of 238U with 46, 53 and 60 MeV 3He ions and the production cross sections for several thorium and actinium isotopes from the irradiation of 238U with 28 GeV protons.