The standard (p degrees = 0.1 MPa) molar enthalpies of formation of crystalline 2-thiophenecarboxamide and 2-thiopheneacetamide were calculated from the standard molar energies of combustion, in oxygen, to yield CO2(g), N-2(g) and H2SO4 center dot 115 H2O(aq), measured by rotating-bomb combustion calorimetry, at T =298.15 K. The vapour pressures of these two compounds were measured as functions of temperature by Knudsen-effusion mass loss technique; from the Clausius-Clapeyron equation the standard molar enthalpies of sublimation, at T = 298.15 K, were derived. The results were as follows: [GRAPHICS] From these values, the standard molar enthalpies of formation of both compounds in their gaseous phase were derived and interpreted in terms of enthalpic increments and molecular structure. (C) 2007 Elsevier Ltd. All rights reserved.