The electrochemical behaviour of magnesium ions was studied in molten CaCl2-NaCl at 550 degrees C by cyclic voltammetry, chronoamperometry and chronopotentiometry. We observed that the electrode process of the reduction of Mg(II) on a tungsten electrode is quasireversible. The values of the transfer coefficient, alpha, and the charge-transfer rate constant, k(0), were calculated by means of the logarithmic analysis of the convoluted curves. Those values were compared with the ones obtained from the steady-state current-potential curves. On the other hand, the diffusion coefficient of the Mg(II) ions, has also been determined by different electrochemical techniques, giving values ranging from 7.2 to 9.9 x 10(-6) cm(2) s(-1)