The metallic fuel in a nuclear reactor is composed of an alloy of uranium and zirconium (5-10 wt%). To understand the feasibility of using room-temperature ionic liquids for reprocessing of spent metallic fuels, the electrochemical behavior of U(IV) and Zr(IV) was studied in the room-temperature ionic liquid, N-butyl-N-methylpyrrolidinium bis(trifuoromethylsulfonyl) imide (C4MPyNTf2). The U(IV) and Zr(IV) ions were introduced into the ionic liquid medium by anodic oxidation of metallic uranium or zirconium as working electrode in the presence of bis(trifuoromethylsulfonyl) imide acid (HNTf2). The U(IV) present in C4MPyNTf2, in the presence and absence of C4MPyCl, was characterized by visible absorption spectroscopy. The voltammetric behavior of U(IV) and Zr(IV) in ionic liquid medium was studied by cyclic voltammetry and chronoamperometry. The U(IV) in ionic liquid was found to undergo a two-step reduction to metallic form at -3.2 V, and Zr(IV) underwent a single-step reduction to metallic form at -1.5 V. The study showed the possibility of using C4MPyNTf2 ionic liquid for electrorefining of metallic fuels. (c) 2018 The Electrochemical Society.