The transient electrochemical behavior of the Yb (III) ion (Yb3+) on the surface of a Ni working electrode in a (LiF–CaF2)eut.–Yb2O3 molten salt system was analyzed using a three-electrode system with a reversible (Ni2+/Ni) internal reference electrode and Pt external reference electrode. The (Ni2+/Ni) internal reference electrode exhibited good stability and reliability, and provided results that were consistent with those of the Pt external reference electrode. The (Ni2+/Ni) electrode also had a wider measurement window for analysis of the electrochemical process than that of the Ni working electrode. Cyclic voltammetry, square wave voltammetry, chronopotentiometry, and chronoamperometry were used to analyze the Yb3+ ion in the (LiF–CaF2)eut. –Yb2O3 (0.03 mol%) system. It was confirmed that the Yb3+ ion was reduced according to Yb3++e→Yb2+ and Yb2++2e→Yb, and the electrode reaction process was quasi-reversible and controlled by diffusion. Moreover, the Yb3+ ion alloyed with the Ni electrode to form a Ni–Yb alloy.