[en] The kinetics of the reduction of Pu(V)O₂⁺ by hydrogen peroxide have been studied in 1.0 m NaCl solutions at 19±2 C. Experiments were conducted over a range of pH values from 7.9 to 10.8 with variable concentrations of hydrogen peroxide between 1.00.10^-5 M and 4.00.10² M. The concentration of plutonium in solution was (1.5±0.2) . 10^-10 M. The decrease of the concentration of PuO₂⁺ in solution with time was monitored by ultrafiltration combined with solvent extraction using TTA. Independent extraction experiments, using DBM as extractant, were employed to validate the results. The reduction of PuO₂ was found to be first order with respect to hydrogen peroxide concentration and inverse first order with respect to hydrogen ion concentration. With these results and assuming a first order dependence with respect to the concentration of PuO₂^-, the reaction can be described by the following rate equation: d[Pu(V)]/dt = k . [Pu(V)] . [H₂O₂]/[H^-], with k = 3.59 . 10^-9 ± 1.79 . 10^-9 min^-1. Using this equation, the redox half life of PuO₂^- has been calculated for a range of environmentally relevant conditions. (orig.)