The electrical conductivity of cryolite systems NaF-AlF3 with cryolite ratio 2.4-3.0containing CaF2 3.°0-7.0 wt %, MgF2 1.2-2.0 wt %, Al2O3 0-8.0 wt % in the temperature range of 700-1050 C has been studied by the impedance spectroscopy. Additions of CaF2and MgF2 to the molten sodium cryolite reduce the electrical conductivity, but below the liquidus temperature in the twoEphase region of solid and liquid phases, the electrical conE ductivity increases with the fluoride salts concentration. The electrical conductivity of cryoE lite systems decreases with increasing Al2O3 content throughout the temperature range.