The standard (p ∘ =0.1MPa) molar enthalpies of formation of crystalline 2-thiophenecarboxamide and 2-thiopheneacetamide were calculated from the standard molar energies of combustion, in oxygen, to yield CO 2 (g), N 2 (g) and H 2 SO 4 ·115H 2 O(aq), measured by rotating-bomb combustion calorimetry, at T=298.15K.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=298.15K, were derived.The results were as follows:Compounds-ΔcUm∘(cr)-ΔfHm∘(cr)ΔcrgHm∘kJ·mol-1kJ·mol-1kJ·mol-12-Thiophenecarboxamide3108.7±1.1171.1±1.2107.1±0.42-Thiopheneacetamide3760.7±1.6197.2±1.8109.2±0.5From 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.