In summary, this research marks a major advancement in the development of medium-temperature PEMFCs. The novel COF ionomer offers solutions to long-standing challenges related to water retention, proton transport, and oxygen mass transport at elevated temperatures. The improved performance of MT PEMFCs using this material opens possibilities for broader applications in the energy sector, particularly in automotive and stationary power generation. This innovation could pave the way for the next generation of PEMFCs, overcoming some of the key obstacles that have limited their application in more demanding applications. Future research should focus on optimizing the synthesis process for large-scale production and exploring the ionomer's performance under a wider range of operating conditions.