Purification of plutonium

A process for the purification of a plutonium-containing aqueous phase during the reprocessing of irradiated nuclear fuel in which the aqueous phase also contains some uranium and neptunium includes the steps of bringing the plutonium-containing aqueous phase into contact with an organic solvent, which solvent comprises a solution of an alkyl ester of phosphoric acid in an organic diluent, to extract plutonium, uranium and neptunium into solution in the organic solvent, bringing the organic solution into contact with a first aqueous phase containing a reductant for neptunium selected from the group consisting of hydroxylamine salts, hydrazine salts and mixtures of hydroxylamine and hydrazine salts at about 30.degree. to 35.degree. C. to extract neptunium into the aqueous phase, separating the organic solution from the aqueous phase, bringing the organic solution into contact with a further aqueous phase containing a reductant for plutonium selected from the group consisting of hydroxylamine salts, hydrazine salts and mixtures of hydroxylamine and hydrazine salts at about 50.degree. C. to extract plutonium into the further aqueous phase and separating the organic solvent from the further aqueous phase.