Abstract：Reducing the operating temperature of ceramic fuel cells (CFCs) from 800° to 1000°C to the 300°-to-500°C range would improve efficiency, sealing, durability, and cost while still maintaining favorable electrode reaction kinetics as compared with those of low-temperature fuel cells such as polymer electrolyte fuel cells. Developing stable electrolytes with a low ionic resistance and negligible electronic conductivity, however, is challenging. In principle, reducing the electrolyte thickness can reduce the resistance. Fabricating an ultrathin electrolyte requires advanced techniques that inevitably make mass production difficult and costly. Developing new high-conductivity electrolyte materials is another way to address this problem. On page 184 of this issue, Wu et al. (1) report a fuel cell with a distinct, high proton conductivity electrolyte.