The standard (p degrees = 0.1 MPa) molar enthalpy of combustion at the temperature 298.15 K of the liquid ethyl 3-oxobutanoate was determined : Delta(0)H(m) degrees = -3149.76 +/- 0.76 kJ.mol(-1), using a static-bomb calorimeter, from which its standard molar enthalpy of formation, in the liquid state, was derived as Delta(f)H(m) degrees(1) = -640.4 +/- 1.1 kJ.mol(-1). The standard molar enthalpy of vaporization, at the temperature 298.15 K, determined by microcalorimetry, was found to be Delta(1)(g)H(m) degrees = 54.18 +/- 0.96 kJ.mol(-1). The standard molar enthalpy of formation of ethyl 3-oxobutanoate was derived for the gaseous keto-enol equilibrium mixture and for the gaseous keto form.