The equilibrium potentials of Bi in a KCl–PbCl2–BiCl3 melt were measured by the EMF method at different temperatures and bismuth chloride contents. Empirical equations of isotherms and polytherms of the equilibrium potentials of bismuth were obtained. The conventional standard potentials of Bi in a molten mixture of potassium and lead chlorides were calculated. The changes in the Gibbs energy during the formation of bismuth trichloride from the elements in the melt were calculated. The coefficients of metal separation from alloys were estimated. The results indicate that it is promising to develop a technology for electrolytic processing of secondary raw materials for separating lead and bismuth in chloride melts.