Energy is a foundation and driving force for the progress of human civilization. It is vital to the national economy, people livelihood, national security, human survival, and development, which is crucial to promoting economic and social development. SOFCs have the advantages of an all-solid structure, high energy conversion efficiency, no need to use precious metal catalysts, easy-to-achieve modularization, flexible fuel types, etc., which are widely used. As a kind of SOFC, protonic ceramic fuel cells (PCFCs) with protons as charge carriers have a unique conduction mechanism and can effectively convert chemical energy into electric energy at relatively low temperatures (i.e., 400?700?°C). The feature that PCFCs can be operated at medium and low temperatures can effectively avoid a reaction between the cell components at high temperatures, making the microstructure more stable while extending the service life. Therefore, PCFCs have attracted recent attention.As one of the core components of PCFCs, the catalytic activity of the cathode is important to the electrochemical performance of PCFCs. The oxygen reduction reaction (ORR) at the cathode of PCFCs is a high-temperature driven process, and the dynamic reaction of ORR at the cathode side of PCFCs becomes slow as the operating temperature decreases and the polarization loss of the cathode increases, resulting in a sharp decline in the electrochemical performance of a single cell at lower temperatures. Therefore, the design of cathode materials with high catalytic activity and stability is one of the effective ways to achieve high-performance low-temperature PCFCs.However, the performance of PCFCs is highly dependent on the material structures of cathodes, which in principle should have sufficient electrical conductivity, structural stability, electrochemical catalytic activity, and durability. Many PCFCs cathodes with a variety of different air electrode structures are developed. This review represents the development on perovskite oxides, double perovskite oxides, RP perovskite oxides, and spinel oxides in PCFCs cathodes, and compared the properties of different cathode materials. Some studies are carried out to modify cathode materials via doping certain elements. The doping of certain elements or compounds can increase the conductivity of the cathode, thereby reducing the resistance and increasing the current density. Also, doping can change the crystal structure and chemical bonding state of the cathode material, improving its stability in different environments. In addition, some dopants may enhance the reaction activity on the cathode surface and reduce the activation energy of the reaction, thus increasing the reaction rate. The preparation of composite structure is also an effective approach to improve the performance of cathode materials. Composite cathodes with comprehensive performance advantages can be constructed via combining different materials with different advantages. In a composite cathode, a synergistic effect can be created between different materials to further enhance the overall performance of the cathode. In addition, the flexible design of the composite structure enables the optimization of the material composition and structure in micron-scale and nano-scale, resulting in the better performance.Summary and prospects Protonic ceramic fuel cells can efficiently convert chemical energy directly into electrical energy, overcoming the potential problems of fuel gas dilution and gas separation in oxygen ion conductor solid oxide fuel cells. However, the electrochemical performance of PCFCs does not exceed that of O-SOFCs, and the development and improvement of cathode materials with a high catalytic activity is the most important issue to promote the development of PCFCs at low temperatures. The future research aspects of PCFCs cathode are as follows: (a) Development and performance of high entropy perovskite oxides. High entropy perovskite oxides can exhibit the properties of many different oxides simultaneously, and achieve a good performance in PCFCs; (b) In-situ characterization and detection of reaction mechanisms. In the future, the in-depth study of in-situ characterization is expected to provide a theoretical support for further understanding of the relationship between electrode structure and performance and further optimization of cathode performance; (c) The development of low-cost cathodes. Cobalt-based perovskite materials are widely used in PCFCs. However, the thermal mismatch between cobalt-based materials and common proton-conducting electrolytes, chemical instability, and rising price of cobalt greatly limit the application of cobalt-based materials in PCFCs cathodes; (d) Optimization of nanostructures. The nanostructured electrodes and interfaces formed via atomic layer deposition or impregnation can increase the number of active sites and reduce the length of ion diffusion to active sites; and (e) Development of composite cathode. The introduction of electrolyte material in the cathode, that is, proton conduction phase, can effectively reduce the polarization resistance of the cathode, expand the length of the three-phase interface, and reduce the thermal expansion coefficient of the cathode, which can better match the electrolyte and solve the problem of delamination between the cathode and the electrolyte.