[en] Full text: Molybdenum-99 (⁹⁹Mo) decays to give technetium-99m (⁹⁹Tc^m), the most versatile diagnostic radioisotope used in approximately 80% of all nuclear medicine procedures. ANSTO (formerly the AAEC) has supplied technetium generators to the medical community since 1967-68. From small-scale beginnings, ⁹⁹Tc^m- generators are now also supplied to customers in New Zealand, Hong Kong, Malaysia, Thailand, Korea and China. ⁹⁹Mo is produced in HIFAR by the fission of uranium-235 (²³⁵U). Uranium (2.2% ²³⁵U) dioxide pellets are irradiated and then chemically processed to separate and purify the ⁹⁹Mo for generator production. The current process involves alumina column separation of ⁹⁹Mo from uranium and other fission products; desorption of ⁹⁹Mo with ammonia; evaporation to dryness to remove volatile impurities; secondary purification of ⁹⁹Mo on alumina. Recent studies have sought to optimize the ⁹⁹Mo yield to meet an increasing market demand. These studies focused on two major stages of the process - alumina column separation and evaporation/ boil down. The effects of changes in pH of loading solution, rates of loading and desorption, volume of eluting solvent and temperature of evaporation have been investigated. The results of tracer and production scale experiments will be presented and the impacts upon future ⁹⁹Mo production in Australia discussed