For the recovery of the electrochemically negative elements, such as alkali and alkaline-earth used in molten salt, it is important to separate them selectively each other. The results of electromigration in molten nitrate system allow us to conclude that the divalent cations were separated from the monovalent ones, because alkaline-earth nitrates were concentrated in the migration tube before the enrichment of Cs. In addition, we have investigated the internal mobilities of Cs in order to estimate the limitation of the enrichment degree. The results enable us to demonstrate that it is feasible to enrich CsNO3 up to x(Cs) = 0.38 in molten LiNO3-KNO3 eutectic. Especially, it was effective to enrich these species under the high current density during electromigration. (C) 2004 Elsevier B.V. All rights reserved.