The sublimation enthalpy of dimethyl oxalate has been measured by calorimetric and head space analysis. These results along with vaporization enthalpy measured by correlation gas chromatography and fusion enthalpy measurements are compared to results predicted by two estimation techniques. A previous experimental measurement was found to be in error. A mean value of (75.2±0.5) kJ/mol was obtained which results in a corrected molar value of (−681.5±0.8) kJ/mol for the enthalpy of formation of gaseous dimethyl oxalate, δf H m o (g, 298.15 K). This new value of δf H m o (g, 298.15 K) for dimethyl oxalate, in combination with other enthalpies of formation, suggests that the ground state of oxalates are destabilized relative to α-diketones by approximately 25 kJ/mol.