Electrochemical techniques such as cyclic voltammetry, stripping voltammetry and square wave voltammetry were used to determine the product of concentration and diffusivity of Ni2+ ions in 62% Li2CO3 + 38% K2CO3 electrolyte mixture under standard gas composition(15% O-2 + 30% CO2) at 650 degrees C. In the case of cyclic voltammetry and stripping voltammetry, dissolved nickel is first deposited on a gold electrode at negative potentials, then dissolved by scanning through positive potentials. Square wave voltammetry is also used as a more precise method to compare the cD(1/2) product between electrochemical techniques. The magnitude of the peak current from current-potential data is related to scan rate, diffusivity and concentration of nickel ions in the melt. Values of cD(1/2) Obtained by these techniques are in good agreement. The saturation concentrations calculated from our measurements (0.5-1 mu mol cm(3)) depend on the diffusion coefficient used in the calculations, but agree with literature values in order of magnitude.