High-temperature devices are eco-friendly devices with the potential to become efficient systems for energy conversion and storage. The stability of components within solid oxide fuel cells and electrolyzers is related to their external operating conditions. The development of robust technologies that select suitable formulations to satisfy operational requirements is a critical issue. The segregation of cations on the surface, particularly of strontium at oxygen electrodes, exsolution of metal particles on anode electrodes, and ion interdiffusion in interlayer regions have a key influence. The segregation and interdiffusion of ions in electrochemical cell materials are critical to the chemical activity and stability of materials, as thermally induced chemical restructuring shapes their microstructure and morphology. The chemical composition of materials is affected by the redistribution of elements between different layers, surface segregation, and metal exsolution. This, in turn, contributes to the formation of low-conducting phases and poisoning phases. In recent years, computational methods and advanced technologies have enabled high-sensitivity examination of the microstructure of ceramic surfaces in the near-surface region. The literature review centers on recent advancements in the study of segregation processes. It covers theoretical calculations and modeling, segregation processes in single crystal and polycrystalline samples, the impact of polarization on cation mass transfer, interdiffusion processes, the influence of atmospheres on the process rates, and the exsolution processes of metal nanoparticles in reducing atmospheres or stepwise exsolution processes in oxidizing atmospheres. This review focuses on recent advances in the study of segregation processes, namely modeling, segregation on single and polycrystalline samples, effects of polarization, interdiffusion, different atmospheres and exsolution of nanoparticles.