The temperature and concentration dependence of resistivity of fused mixtures of NaF-NaCl-HfF4 is studied by the relative capillary method. Molar electric conductivity and activation energy of all mixtures are computed on the basis of investigation results and density values of fused mixtures are defined. The significant deviations of molar electric conductivity from additive magnitudes point to formation of complex ions in the fused mixtures during the components mixing.