Abstract Hydroxamic acids are promising complexant based alternatives to the reductant (U⁴⁺ or Fe²⁺) based selective stripping of Np (and Pu) from a uranium loaded 30% TBP/OK solvent during the reprocessing of irradiated nuclear fuels. Acetohydroxamic acid (AHA) has the benefits of being both a reductant and complexant that efficiently strips Np (and Pu) from solvent phase without adding salt wastes to actinide separation processes. To model these processes, an understanding of Np-hydroxamate chemistry in aqueous and organic solvent is necessary. Three aspects of this system are discussed.