Two of the major consequences of neutron-induced nuclear reactions with natural uranium targets, nuclear ssion and production of trans-uranium elements, have contributed signicantly to the separation chemistry of actinides. Since the early days of the Manhattan Project, much of the interest centered on the separation of trace amounts of plutonium from a large excess of uranium and a moderate concentration of ssion and decay products. Solvent extraction and ion exchange have played a key role in isolation, separation, and purication of uranium and plutonium, both at analytical and industrial scale. Sustained interest in improved nuclear fuel-reprocessing methods and growing concern for the fate of actinides at potential waste-disposal sites provide continuous motivation for investigating the complexation and separation behavior of actinides. Separation chemistry of actinides plays a pivotal role at different stages of the nuclear fuel cycle: (a) recovery and purication from ores, (b) chemical quality control of nuclear fuels, (c) fuel reprocessing, and (d) waste management. Apart from these applications, the actinides display a fascinating chemistry in solution (e.g., disproportionation, variable oxidation state, colloid formation, and polymerization), which provides sufcient justication for solution chemists to investigate their basic complexation and separation behavior (1).