Solid oxide electrolyzer cells with an Ni-Fe-yttria-stabilized zirconia (Ni-Fe-YSZ) hydrogen electrode as the cathode, lanthanum strontium ferrite (LSCF)-gadolinia-doped ceria (GDC) air electrode as the anode, and YSZ as the electrolyte were fabricated, and the oxidation protection effect of sacrificial Fe particles was investigated. X-ray diffraction analysis indicated that Ni was protected from oxidation under a water vapor atmosphere by sacrificial Fe. Scanning electron microscopy observations suggested that the Ni particles accumulated in the Ni-YSZ hydrogen electrode, which might have been associated with the partial oxidation of Ni during cell operation at 700 °C in 50% H₂O/15% H₂/35% Ar atmosphere. No appreciable microstructural changes were observed for the Ni-Fe-YSZ hydrogen electrode. Furthermore, the presence of the sacrificial Fe particles could be responsible for the superior durability of the cell, compared with that of the cell featuring the conventional Ni-YSZ hydrogen electrode.