The present work reports the values of the gaseous standard (p ∘ =0.1MPa) molar enthalpies of formation of the three acetylpyridine isomers, at T=298.15K. For each isomer, that value was derived from measurements of the standard molar energy of combustion of the corresponding liquid, using a static bomb calorimeter, together with measurements of the standard molar enthalpy of vaporization, measured by Calvet microcalorimetry. CompoundΔcHm∘(l)/kJ·mol-1ΔlgHm∘(T=298.15K)/kJ·mol-12-Acetylpyridine−3653.2±2.760.5±0.33-Acetylpyridine−3653.7±2.566.1±0.84-Acetylpyridine−3652.3±1.666.5±0.9