The initial thermoelectric power of the molten salt mixtures (Ag + Me)Cl (Me = Li, Na, Rb, Cs) has been measured at various temperatures around 800 °C using a silver electrode thermocell. In addition the thermoelectric power of molten pure AgCl is reported. These data have been used to obtain relative values of the heats of transport of the alkali cations in pure salts. Moreover the global behaviour of these mixtures in respect to an ideal model for the heat and electricity transport is discussed.