Electron and ion transfer numbers, electroconductivity, density, and concentrations of Cu+ and Cu2+ in molten salt mixtures of CuCl-CuCl2-MeCl (Me = Li, Na, K, Cs) were measured at a partial pressure of chlorine over the melt equal to the atmospheric pressure in the temperature interval from 800 to 1000 K. Partial values of ion and electron transfers and the molar volume of the melts were determined. Mobility of electrons was estimated. The electron transfer number was a maximum in the CuCl-CuCl2 Melt with t(c) equal to 0.9. When chlorides of alkali metals were added to the CuCl-CuCl2 melt, the electron component of electroconductivity was preserved up to 90, 65, 60, and 50 mol.% LiCl, NaCl, KCl, and CsCl, respectively. A mechanism of the electron transfer in the test melts was proposed. (C) 2003 Elsevier Science Ltd. All rights reserved.