To support the proposal for separating uranium from used fuel salt of Molten Salt Reactor (MSR), the electrochemical behavior of UO22+ in the carrier salt of MSR (LiF-BeF2, FLiBe) was investigated in this work. Cyclic voltammetry and square wave voltammetry measurements showed that the reduction of UO22+ in UO2F2-FLiBe melt with addition of KF exhibited one step with two exchanged electrons: UO22+ + 2e(-) -> UO2, with reduction peak of 1.93 V (vs. Be2+/Be). By potentiostatic electrolysis, the product of octahedral UO2 single crystals with micron size was obtained. (C) 2019 The Electrochemical Society.