The kinetics of the reduction of plutonium(IV) by hydroxyurea (HU), a novel salt free reductant, in nitric acid solutions
has been studied. The observed reaction rate can be expressed as: -d[Pu(IV)]/dt=k0[Pu(IV)]2[HU]/[H+]0.9, where k0 = 5853±363 (l1.1.mol-1.1.s-1) at t = 13 °C. The activation energy is about 81.2 kJ/mol. The study also shows that uranium(VI) has no appreciable influence on
the reaction rate. Compared with other organic reductants our experiments indicate that HU is a very fast reductant for plutonium(IV).