AbstractThe electrical properties of composite electrolytes (suspensions) composed of α-Al2O3 powder and molten carbonate eutectic (Li2CO3–Na2CO3–K2CO3)eut or molten carbonate–chloride mixture 0.72(Li2CO3–Na2CO3–K2CO3)eut–0.28NaCl have been investigated by AC impedance method. This system shows a dependence of the electrical conductivity upon the temperature and the α-Al2O3 content. The specific electrical conductivity of the α-Al2O3/(Li2CO3–Na2CO3–K2CO3)eut system can be adequately described by the Maxwell equation for two-phase heterogeneous materials. The regression equation for the dependence of the specific conductivity of the α-Al2O3/(Li2CO3–Na2CO3–K2CO3)eut composite on the aluminium oxide concentration and temperature was obtained.