An electrolyte-supported solid oxide electrolysis cell (SOEC) consisting of a ScSZ (Sc2O3-stabilized ZrO2) electrolyte, Ni-YSZ cathode and LSCF (lanthanum strontium cobalt ferrite)-GDC (Gd2O3-doped CeO2) anode was fabricated. Current density-voltage (j-V) curves were obtained for the cell under SOFC and SOEC modes and the cell performance was discussed in combination with corresponding EIS measurements. It was possible to determine the ohmic, cathodic and anodic contributions to the total polarization loss using the three-electrode technique. It was found that the overpotential of the Ni-YSZ electrode contributed largely to the performance of the cell.