Separation of Am-241(III) from Eu-152,154(III) was carried out using an improved system of flow-counterbalanced capillary electrophoresis in a thiocyanate medium. In this system, Eu-III was electrophoresed in the opposite direction to Am-III, due to a combination of (1) the difference in the moving velocities of Eu-III and Am-III, and (2) a constant flow in the capillary caused by a difference in the water levels of the inlet and outlet of the sample solution.