<p>The kinetics of Pu(VI) and Pu(IV) reduction by carbohydrazide and diformylhydrazine in a perchloric acid has been investigated spectrophotometrically. The reaction orders with respect to each reactant (plutonium, reductant and perchloric acid) have been determined. Final products of plutonium reduction, reaction stoichiometry and activation energy have been evaluated. The observed differences in reaction kinetics between perchloric/nitric acid highlight the distinct effects of medium composition on the redox behavior of plutonium. The insights gained in perchloric acid provide a foundation for understanding how complexation in nitric acid might modulate these reactions under industrial conditions during reprocessing of spent nuclear fuel.</p> Graphical Abstract <p></p>