What substance has the highest calorific value?

The substance with the highest calorific value is generally considered to be hydrogen, which has a calorific value of about 141.9 megajoules per kilogram (MJ/kg) when combusted. In practical terms, when comparing traditional fuels, acetylene has one of the highest calorific values at around 50 MJ/kg. However, for conventional fuels, gasoline and kerosene also have high calorific values, ranging from 44 to 47 MJ/kg.