Abstract: Using RBC-Ⅱ type oxygen-bomb combustion calorimeter, the molar combustion enthalpies of room temperature ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate (EMIES), and 1-methylimidazole were determined at T=(298.15±0.01) K. For EMIES =(－2671±2) kJ·mol－1 and for 1-methylimidazole (－286.3±0.5) kJ·mol－1, respectively. The standard formation enthalpies were calculated to be (－3060±3) kJ·mol－1 for EMIES and (－2145±4) kJ·mol－1 for 1-methylimidazole. The reaction: ＋ (C2H5)2SO4 → [ ＋ C2H5OSO3－ ](l) is strong exothermic and its reaction heat, , was determined to be (－102.3±1.0) kJ·mol－1. The standard formation enthalpy of EMIES, ΔfHT, at different temperatures was calculated on the basis of the heat capacity data of EMIES.

Key words: Ionic liquid, 　Oxygen-bomb combustion calorimeter, 　EMIES, 　Standard molar enthalpy of combustion, 　Standard molar enthalpy of formation