Energy of combustion of 4-nitroimidazole was measured by static bomb calorimetry. Enthalpy of sublimation of 4-nitroimidazole was determined by Calvet microcalorimetry. Gas-phase enthalpy of formation of 4-nitroimidazole derived from experimental measurements. Gas-phase enthalpies of nitroimidazole isomers formation estimated from G3 calculations.