Solid Oxide Fuel Cells are electrochemical devices that convert the chemical energy contained in a fuel/oxidizer pair, generally H2/O2, into electrical energy. They received a great deal of attention due to their high electrical efficiency (60%), durability, low cost and flexibility in the choice of fuel.1 The main specificity of SOFCs is a high operating temperature between 700 °C and 1000 °C, dictated by the ionic conduction of yttrium stabilized zirconia (YSZ), the reference electrolyte. A recent study showed that a bi-layer electrolyte based on stabilized bismuth oxide and stabilized ceria has led to a significant improvement with a specific power density of ~1 W.cm-2 at 650 °C. 2 In 2013, devices capable of operating at 550 °C were even marketed, thus opening up new perspectives for ionic conductors derived from bismuth oxide, widely studied at UCCS 20 years ago. These materials present ionic conductivities several order of magnitude higher than YSZ but have been neglected in recent years due to their instability in a reducing atmosphere. As part of the BIBELOT grant (ANR-18-CE05-0001), which aims at finding new cathode materials for this type of device, we initially considered the development of a two-layer electrolyte Er0.5Bi1.5O3/ Gd0.1Ce0.9O1.95 (ESB/GDC). For the fabrication and deposition of the ESB on GDC, the ESB powder was synthesized at temperatures as low as 500 °C using wet chemical co-precipitation and sol-gel procedure in order to minimize the grain size and therefore obtain a dense ESB layer. We will present here the first results obtained by spin coating on a dense electrolyte of GDC of an ink prepared from this ESB powder. Acknowledgement 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.