A novel fuel electrode-supported electrolysis cell has been developed as promising candidate for hydrogen production at intermediate temperatures. It contains a Ni-GDC electrode functional layer, a three-layer GDC-YSZ-GDC electrolyte and an LSC air electrode. Although this cell enables improved performance compared to state-of-the-art YSZ electrolyte-based cells, especially at lower operation temperatures, 700 °C and below, and electrolysis currents around 1.2-1.7 A cm-2 a voltage drop and subsequently crack formation in the electrolyte was observed in initial studies. In the current work, FIB/SEM and X-ray computed tomography are used for microstructural investigations. Based on calculated microstructural parameters the suitability of the methods for an assessment of the failure mechanisms are discussed.