The present paper suggests a novel salt-free organic agent to separate U and Pu in HNO3 solution. This agent is hydroxyurea(HU) which has strong reduction ability and also is a good chelating agent with a relatively simple structure. HU can rapidly reduce Pu(IV) to Pu(III) in HNO3 solution. The reduction can be to such extent that almost 100% Pu(IV) can be reduced to Pu(III) in 0.5 mol/L and 3.0 mol/L HNO3 solution. With the concentration less than 1.0 mol/L, HU has The present paper suggests a novel salt-free organic agent to separate U and Pu in HNO3 solution. This agent is hydroxyurea (HU) which has strong reduction ability and also is a good chelating agent with a relatively simple structure. The reduction can be to such extent that almost 100% Pu (IV) can be reduced to Pu (III) in 0.5 mol / L and 3.0 mol / L HNO3 solution. With the concentration less than 1.0 mol / L, HU has