In this paper, we develop and experimentally investigate a novel hybrid ammonia fuel cell and thermal energy storage system. A molten alkaline salt is utilized for storing thermal energy as well as operating an alkaline electrolyte-based direct ammonia fuel cell. The specific thermal energy storage capacity of the hybrid system is found to be 133 kJ kg(-1) at a temperature of 320 degrees C. Furthermore, the maximum power densities are found to be 2.1 +/- 0.1 W m(-2) to 2.3 +/- 0.1 W m(-2) for operating temperatures varying between 220 degrees C and 320 degrees C. The energy efficiency is evaluated as 20.6 +/- 0.6%, and the exergy efficiency is determined to be 23.3 +/- 0.7% at the peak power density.