Closing the nuclear fuel cycle in the US poses many challenges, one of which is found in the waste streams, which contain both trivalent lanthanides and actinides. The separation of americium from the raffinate will dramatically reduce the long-term radiotoxicity of the waste. The sorption of americium in both the tri- and pentavalent oxidation states was observed for four M(IV) phosphate-phosphonate ion exchange materials in nitric acid at pH 2. High selectivity was observed for reduced Am(III) with Kd values ca. 6×10 5 mL/g, while the Kd values for Am(V) were much lower. A new method of synthesizing and stabilizing AmO2 + to yield a lifetime of at least 24 h in acidic media using a combination of sodium persulfate and calcium hypochlorite will be described. © by Oldenbourg Wissenschaftsverlag, Mülnchen.