The irradiation of highly enriched Ca 48co3 with a bremsstrahlung beam of maximum energy 46 Mev produced Ca47 with a yield of 1. 1 to 3 . O uc/mg Ca48 at half-saturation. The half-life of a sample measured through aluminum absorber to eliminate the contribution by the sc47 daughter was 4. 51 ±. 0 . 02 days . By comparison with the Cu63( 7, n)Cu62 reaction the integrated cross section from 0 to 46 Mev for the sum of the reactions ca48( 7, n)Ca47 and Ca48( 7', p)K47 was calculated to be 29 Mev-mbarn. The Ca46 content of the sample calculated to the end of the bombardment was,.. 0. 040/o, probably the result of the Ca 48 ( ?', 3n) and ( 7, p2n) reactions.