Evidence is obtained to show that the liquidliquid extraction separation of99mTc from99Mo with methyl ethyl ketone, methyl propyl ketone and methyl isobutyl ketone can be transformed into a solid-phase column extraction procedure. The aqueous alkaline99molybdate solution is immobilized on a column of a granular large-pore diatomaceous earch support, which is the neluted with the abovementioned extractants. Rapid and clean separation of99mTc can be with all three solvents. The99mTc can be back-extracted from the organic phase on a column filled with distilled water /or saline/ loaded granular diatomaceous earth /Extrelut®/. The possibility of using the abovementioned procedure as a basis for a new99mTc/99Mo generator concept is envisaged.