⁶⁴Cu (t_1/2 12.7 h) is a versatile radionuclide owing to its unique decay scheme and exhibits three types of decay electron capture (41%), b^- (40%), b^? (19%) that is useful in nuclear medicine applications. Different batches of natural copper oxide (CuO) and 99.9% enriched ⁶³CuO targets were irradiated in research reactors at a neutron flux of 6.6 9 10¹² n cm^-2 s^-1 for duration of 3 days. Irradiated samples dissolved in hydrochloric acid solution were measured in HPGe-MCA system, the activity of ⁶⁴Cu, co-produced radionuclide impurities and radionuclide purity was determined. Average specific activity of 254 GBq ⁶⁴Cu per g Cu and*348 GBq ⁶⁴Cu per g Cu was recorded at the end of irradiation from natural and enriched CuO targets, respectively.