What substance has the highest specific heat?

The natural substance with the highest specific heat capacity is liquid ammonia, with a specific heat of 4.7 J/g K. The substance with the second-highest specific heat is liquid water at 4.18 J/g K.

Specific heat capacity, commonly called specific heat, is the amount of heat required to change a mass of a substance by a certain temperature. It is usually measured by the number of Joules required to raise the temperature of a gram of material by one degree Kelvin (or Celsius). Water has an unusually high specific heat, and the human body is mostly water, meaning that humans can absorb or lose a lot of heat without drastic changes in internal temperature.