Abstract: The electric conductivities of molten KCl-NaCl (1:1mol)-RECl₃ weremeasured by the A.C.bridge method. The following empirical expression ofthe specific conductivity κ of the melt was obtained as a function of tem-perature:κ=A+B(t-700) where t is temperature (from 700℃ to 850℃), A and B are constant givenin the paper. The deviation of the obtained values from the calculated (forthe concentration of rare earth chlorides 10-50wt%) was discussed in viewof the possible formation of a complex.