Enthalpies of combustion of methyl benzoate (I), methyl o-toluate (II), methyl m-toluate(III), methyl p-toluate (IV), monomethyl terephthalate (V), dimethyl phthalate (VI), and trimethyl 1,2,4-benzenetricarboxylate (VII) have been determined using bomb calorimetry. Enthalpies of evaporation of these substances (I-VII), and also of dimethyl terephthalate (VIII) and dimethyl isophthalate (IX), have been measured calorimetrically. Standard molar enthalpies of formation in the gas phase have been calculated tin kJ.mol(-1)) : (I) (-277.7 +/- 1.3), (II) (-301.5 +/- 1.9), (III) (-309.6 +/- 1.6), (IV) (-308.7 +/- 1.6), (V) (-648.7 +/- 2.3), (VI) (-606.2 +/- 2.6), (VII) (-963.3 +/- 2.9), (VIII) (-627.4 +/- 1.1), and (IX) (-627.1 +/- 1.1). Values of additive constants have been obtained to calculate enthalpies of formation of methyl esters of benzene carboxylic acids in the crystal and gas states.