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The joule per mole (symbol: J/mol, J·mol⁻¹) is an SI derived unit of energy per amount of material. Energy is measured in joules, and the amount of material is measured in moles.

Physical quantities measured in J·mol⁻¹ are usually free energies, such as:

• Heat of vaporization
• Heat of fusion
• Ionization energy

For convenience and due to the range of magnitudes involved, these quantities are nearly always quoted in kJ/mol. For example, heats of fusion and vaporization are usually of the order of 10 kJ/mol, bond energies are of the order of 100 kJ/mol, and ionization energies of the order of 1000 kJ/mol.

1 kJ/mol is equal to 0.239 kcal/mol or 10.4 meV per particle. At room temperature (25 °C, 77 °F, or 298.15 K) 1 kJ/mol is equal to 0.4034 k_BT.