In the present study, solid oxide cells (SOCs) were operated in electricity generation (solid fuel cell, SOFC) mode and hydrogen production electrolysis SOEC) mode. The electrodes fabricated with nickel-gadolinia doped ceria (Ni-GDC) nickel-yttria stabilized zirconia (Ni-YSZ) composites investigated. correlations between changes microstructure degradation of electrochemical performance are disc...