Solubility and electrochemical properties of Nb3Cl8 in LICl-KCl eutectic melt were examined. It was found that the maximum solubility of Nb3Cl8 is not higher than 0.8 wt% within the 400-500 degrees C temperature range. At a tungsten electrode, Nb3Cl8 is reduced to metallic niobium through two consecutive electrochemical steps: a first reversible step involving one electron charge transfer and a second rather irreversible step implying two electrons number exchange and yielding to metallic niobium. This last step is perturbed by the formation of niobium subhalide insoluble compounds(cluster). The diffusion coefficients of the Nb(III) and Nb(II) species were found equal to 2.6 x 10(-6) and 3 x 10(-6) cm(2) s(-1), respectively. According to these values, it was concluded that diffusive species are complexes rather than simple ones.