Abstract: The behavior of germanium and gallium on several kinds of supports is investigated. Three 68Ge/68Ga generator systems are tested: calcium carbonate-calcium hydroxide, active carbon-calcium hydroxide and cerium dioxide-HC1. A generator based on the cerium dioxide support is the comparative, which yields>60% of the 68Ga formed and less than 0. 05% of the 68Ge fixed in the first 3 ml 0. 02 mol/1 HC1 aqueous eluate.