Abstract: This work is a preliminary investigation on the application of aceto and propionylhydroxamic acid as complexing agents of Pu for the improvement of U/Pu separation. The effects of varying complexing agents and nitric acid concentration, HDBP concentration, phase ratio, temperature and standing time on D (Pu(Ⅳ)) are studied in detail for the extraction and stripping of Pu by TBP. The extraction behavior of Pu(Ⅳ) of various valent states has been investigated with acetohydroxamic acid as well. The single stage distribution experimental results show that the above two hydroxamic acids are very strong complexing agents for plutonium.