The stability of bismuth chloride and oxide and the electrochemical reduction of Bi3+ ions in a PbCl2 + KCl equimolar mixture at 475-degrees-C were investigated using potentiometry, cyclic voltammetry, chronoamperometry and chronopotentiometry. The standard potential of the redox couple Bi(III)/Bi(0) and the solubility product of bismuth oxides were determined (E-degrees-Bi(s)/Bi(II) = - 0.92 +/- 0.01 V (vs. Cl2 (1 atm)/Cl-), pK(s) = 4.9 +/- 0.1 (molality scale). A potential-oxoacidity diagram of bismuth is given. Bismuth (III) reduction involved a single three-electron transfer process at a tungsten electrode. The diffusion coefficient of Bi(III), the thickness of the diffusion layer by thermal convection and other kinetic parameters were also calculated.