The project entitled: “Catalytically active nanoparticles exsolved from double perovskite lattice for biogas-fueled SOFC” is focused on the synthesis of Sr2Fe1.5Mo0.5O6 double perovskite doped with transition metals such as Ni, Co, or Cu. In a reductive atmosphere, transition metals will undergo an exsolution process, in which catalytically active nanoparticles will be formed. Sr2Fe1.5Mo0.5O6-based compounds are characterized by high electronic conductivity in both oxidizing and reducing atmospheres and high redox stability, making it a promising material for SOFC electrodes. Double perovskite-based material will be used as both the cathode and the anode in the electrode-supported Solid Oxide Fuel Cell (SOFC), resulting in the formation of a quasi-symmetrical cell. During the project implementation, the compound composition, synthesis and reduction conditions will be optimized toward best performance. Synthesized materials will be fully characterized to reveal the most promising candidates for further research work. The compounds will each time be subjected to XRD and SEM measurements. Electrochemical properties will be established using electrical measurements, e.g.: Van der Pauw, Electrochemical Impedance Spectroscopy (EIS), or Electrical Conductivity Relaxation (ECR). The proper characterization of materials also requires the use of XPS spectroscopy and TPR, TPO TPD techniques to determine the oxidation state of elements at the B-site and the oxygen non-stoichiometry. Several thermal analyses will be also applied: TG/DSC to determine possible phase changes and dilatometry to measure thermal expansion coefficient. Compounds with the most promising properties will be mixed with La- or Nd-doped ceria to form a composite and then symmetrically deposited on LSGM electrolyte. The performance of the novel cells will be measured under typical conditions with hydrogen working as a fuel, and also when SOFC will be fed with synthetic biogas. Long-term stability tests will be performed, in order to determine the degradation rate and the sulfur tolerance will be determined under controlled contamination of fuel with H2S. The successful completion of the described project will result in deep insight into the properties of double perovskite-based material and a better understanding of its properties. Hopefully, synthesized composites will be characterized by better performance in SOFCs, fueled by biogas than conventional state-of-the-art electrodes.