The general regression equations basic physical and chemical properties (liquidus temperature, conductivity, solubility of alumina) mixed potassium-sodium cryolite melts with cryolite ratio 1.3-1.5 with additives LiF and CaF2 are investigated and described. Based on the identified patterns the electrolyte composition, promising for low-temperature aluminum electrowinning  are defined: KF-AlF3 and KF-NaF-AlF3, containing 12-15 wt.% NaF, with cryolite ratio of 1.3-1.5 and the liquidus temperature below 800 C. The solubility of alumina in electrolytes such is not less than 4.5 wt.% in the temperature range of 700-800 C. In order to increase the electrical conductivity supplements LiF in an amount of not more than 3 wt.% are recommended. CaF2 in the presence of the electrolyte is not desirable.