The standard molar enthalpy of formation in the gaseous state (-613.5 +/- 2.2) kJ center dot mol(-1) of levulinic acid has been obtained from combustion calorimetry and results from the temperature dependence of the vapour pressure measured by the transpiration method. In order to verify the experimental data, first-principles calculations have been performed. Enthalpies of formation derived from G4 and G3MP2 methods are in an excellent agreement with the experimental results. Thermodynamic analysis of the hydrolysis of 5-hydroxymethylfurfural to the levulinic and formic acids has revealed very high feasibility of these reactions with equilibrium constants completely shifted to the desired reaction products even at T = 298.15 K. (C) 2011 Elsevier Ltd. All rights reserved.