Exsolution has recently emerged as a powerful and versatile strategy for tailoring the surface of functional oxides with catalytically active nanoparticles, offering new opportunities in energy conversion and storage. In this study, we employed advanced chemical synthesis routes to systematically investigate the role of co–doping with transition metals (Ni, Fe, Cu) and noble metals (Pt, Pd) in yttrium–doped barium cerate–zirconate perovskite (Ba_1-wCe_xZr_yY_zMe₁_-x-y-zO₃_-δ), synthesized via sol–gel, [1] and in gadolinium–doped ceria fluorite (Ce_xGd_yMe₁_-x-yO_2-δ), prepared by microwave–assisted polyol synthesis. [2] These materials are increasingly relevant as electrolytes and electrocatalysts, particularly BaCe_xZr_yY_zO₃_-δ is widely implemented in protonic electrochemical energy conversion devices, hydrogen separation membranes, ammonia synthesis and cracking catalysts, while Ce_xGd_yO_2-δ finds important applications as an electrolyte in solid oxide cells, catalytic supports, and oxygen separation membranes. Perovskite or fluorite formation, dopant incorporation, and crystallinity were characterized by XRD, while stoichiometry was confirmed via ICP–OES. Calcination conditions and thermal stability were assessed through TG–DSC, followed by exsolution via thermal treatment under a reducing atmosphere (900 °C, 12 h, 5% H₂/Ar). The resulting oxide matrices and exsolved nanoparticles were examined using FESEM–EDX. Because Ba–based perovskites are particularly prone to CO₂ attack at the 500–700 °C operating window of intermediate-temperature solid oxide cells (IT–SOCs), we further evaluated their carbonation resistance through TG cycling tests in CO₂ atmosphere, probing the effects of dopant chemistry and stoichiometry on repeated carbonation–decarbonation cycles and on the kinetics of CO₂ adsorption/desorption. Finally, the catalytic performance of exsolved Ba_1-wCe_xZr_yY_zMe₁_-x-y-zO₃_-δ in ammonia cracking and synthesis is under exploration, with preliminary results revealing strong dependencies on synthesis route, calcination temperature, and especially dopant type. Overall, this work establishes clear correlations between doping strategies, exsolution–driven nanostructuring, and functional performance, paving the way for the design of next-generation catalysts and electrocatalysts with improved efficiency and durability, as well as robust ionic conductors for electrochemical energy conversion and gas separation technologies.