Thermal batteries are single discharge reserve batteries that provide very long shelf life, minimal self-discharge, wide storage temperature range, fast activation under sudden power demand, and also wide range of temperature operating conditions. Such unique properties among electrochemical power systems are provided with application of molten salt electrolyte, which is in solid form under normal storage conditions. Upon activation, thermal batteries are heated with an internal pyrotechnic heat charge above melting temperature of the molten salt electrolyte. This allows for fast ion mobility and facilitates charge transfer reaction. Due to the unique properties, thermal batteries are primarily used in DoD applications, specifically in munitions and weapon systems. Modern applications and their latest development call for rechargeable high performance, cost efficient, and reliable thermal batteries. We are proposing development and characterization of rechargeable thermal battery, which addresses the described needs and properties. The proposed solution addresses growing market segment, and it is required for the latest military applications and newly developed systems. Along with our development in Phase I and Phase II, we will aim for fully functional prototypes and field tries, and market of our technology to DoD agencies.