Hydroxamic acids can act as both complexing agents and reducing agents for actinide ions. In HNO3, Pu(IV) ions form strong dark red complexes with formo- and aceto-hydroxamic acids, which on standing convert to blue Pu(III) nitrate ions. In acid solution, these hydroxamic acids also hydrolyse to the parent carboxylic acid and hydroxylamine. The rate of hydrolysis varies depending on the substituents within the hydroxamate and whether the hydroxamate is free or bound to a metal ion centre. We have qualitatively shown that the observed rate of reduction of the Pu(IV)-FHA complex is most probably controlled by the hydrolysis reactions of the hydroxamic acid.