The electrochemical redox process Eu(III) + e(-) double left right arrow Eu(II) in an equimolar NaCl-KCl melt in the temperature range 973-1123 K on glassy carbon electrodes was studied by linear sweep voltammetry, cyclic voltammetry, chronopotentiometry and reversal chronopotentiometry. it was determined that at a sweep rate of nu less than or equal to 0.1 V s(-1), the electroreduction of Eu(III) to Eu(II) is reversible, but at 0.1 < nu less than or equal to 0.3 V s (-1), mixed diffusion and electron-transfer control is observed. Further increase of polarization rate, nu greater than or equal to 0.5 V s (-1) results in electron-transfer control. The diffusion coefficients of Eu(III) and Eu(II) were determined by linear sweep voltammetry and chronopotentiometry methods. The values found by these methods are in a good agreement with each other. The diffusion coefficients of Eu(III) and Eu(II) in the NaCl KCl melt are discussed in connection with the strength and stability of these complex ions. The standard rate constants for the reduction of Eu(III) to Eu(II) were calculated on the basis of cyclic voltammetry data. The sluggish kinetics of this reaction is discussed in terms of substantial rearrangement of the europium coordination sphere. The formal standard redox potentials of E*(Eu(III) Eu(II)) were determined from linear sweep voltammetry and cyclic voltammetry. (C) 2001 Elsevier Science Ltd. All rights reserved.