The standard molar enthalpy of formation, Delta(f)H(m)degrees(l), of the ionic liquid 1-ethyl-3-methylimidazolium thiocyanate has been determined at T = 298.15 K by means of rotating-bomb combustion calorimetry. The enthalpy of formation of this ionic liquid in the gaseous phase, Delta(f)H(m)degrees(g), was obtained using the value Delta(f)H(m)degrees(1) and the enthalpy of vaporization of 1-ethyl-3-methylimidazolium thiocyanate available from the literature. First-principles calculations of the ionic pair of the ionic liquid 1-ethyl-3-methylimidazolium thiocyanate have been performed using the G3MP2 theory. Close agreement of the molar enthalpy of formation, Delta(f)H(m)degrees(g), from experiment and from the high-level first-principles method G3MP2 allows us to conclude that this method seems to be suitable for calculation of the thermodynamic properties of sulfur-containing ionic liquids in the gaseous phase.