The extraction of U(VI), Np(IV), -(V), -(VI), and Pu(IV) and -(VI) by
secondary alkylamines (dioctylamine and didecylamine) from HNO3 and H2
SO4 solutions containing the ''unsaturated'' heteropolycompound K10P2W
17O61 is studied. The studied extraction system can be used to separat
e U, Np, and Pu and to isolate them from rare-earth and transplutonium
elements.