Vapour pressures of 1,3,5-trimethoxycarbonylbenzene, 1,3,5-C6H3(COOCH3)(3); 1,2,4,5-tetramethoxycarbonylbenzene, 1,2,4,5-C6H2(COOCH3)(4); pentamethoxycarbonylbenzene, C6H(COOCH3)(5); and hexamethoxycarbonylbenzene, C-6(COOCH3)(6), have been determined, over a 20 K temperature interval, by the Knudsen-effusion technique. From the experimental results of this work and our previously published thermochemical quantities, the standard molar enthalpies of sublimation, and formation in crystalline and gaseous state at the temperature 298.15 K, have been derived.