The detonation energies of several high explosives are evaluated from the results of chemical-equilibrium computer code named EXPLO5. Two methods of the evaluation of detonation energy are applied: (a) direct evaluation from the internal energy of detonation products at the CJ point and the energy of shock compression of the detonation products, i.e. by equating the detonation energy and the heat of detonation, and (b) evaluation from the expansion isentrope of detonation products, applying the JWL model. These energies are compared to the energies computed from cylinder test derived JWL coefficients. It is found out that the detonation energies obtained directly from the energy of detonation products at the CJ point are uniformly to high (0.9445 +/- 0.577 kJ/cm(3)), while the detonation energies evaluated from the expansion isentrope, are in a considerable agreement (0.2072 +/- 0.396 kJ/cm(3)) with the energies calculated from cylinder test derived JWL coefficients.