The electrical conductivity of low-temperature electrolytes based on Na3AlF6 was measured by means of a tube-type cell. ACtechniques with a sine wave signal in the high frequency range were applied. Basic binary melts NaF-AlF3 were studied at different molar cryolite ratios MR = (2.0-1.2) in the temperature range from the temperature of primary crystallization to 100 degrees C overheat. The influence of the additions of 2 wt% of Al2O3, 5 wt% of CaF2 or 2 wt% of MgF2 was investigated at the same conditions, as well. The temperature and concentration dependencies of the conductivity in the studied systems were determined. (C) 2017 The Electrochemical Society. All rights reserved.