Solid Oxide Fuel Cells (SOFC) have received great attention this decade due to their high electrical efficiency (60%), their durability, their low cost and their flexibility on the nature of the fuel used (hydrogen, methane,…).1 The reference electrolyte used in these cells is Zr1.92Y0.08O3.96 (YSZ). It is the ionic conductivity of this component that limits the temperature range above ~700 °C. However, the high operating temperature of SOFC can result in cost limitations and operating complexities. In order to decrease the operating temperature, a recent study has shown that by using a bilayered electrolyte, formed of erbium stabilized bismuth oxide (ESB) and gadolinium doped ceria (GDC), it is possible to drop the operating temperature down to 350 °C. The bilayered electrolyte has led to a significant improvement reveiling to a specific power density of ~1 W.cm-2 at 650 °C.2 This study focuses on the fabrication and deposition of thin and dense bilayer electrolytes ESB/GDC. GDC pellets were prepared and sintered at different temperatures. An optimized grain microstrucure and density was obtained at 1300 °C. In order to maximize the size of the ESB powder, the latter was synthesized at temperature as low as ~500 °C using wet chemical co-precipitation (ESB-cp) and sol-gel procedure (ESB-sg). Due to its high sinterability, the ESB-sg was used to prepare the ink and dense ESB layers deposited with the spin coater which were obtained at a sintering temperature of 900 °C. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX) showed a good interface between the ESB and GDC layers. Acknowledgements CNRS, Ministère de l'Enseignement Supérieur et de la Recherche and Agence Nationale de la Recherche and BIBELOT ANR-18-CE05-0001 are acknowledged for funding. References [1] D. M. Bierschenk, J. R. Wilson and S. A. Barnett, Energy Environ. Sci., 2011, 4, 944–951. [2] E.D. Wachsman, K.T. Lee, Science, 334 (2011), 935-939.