The Knudsen mass-loss effusion technique was used to measure the vapor pressures, between 0.1 Pa and 1 Pa, of the three monomethyl benzenedicarboxylates over the following temperature intervals: monomethyl phthalate, between 335.28 K and 355.28 K; monomethyl isophthalate, between 359.26 K and 379.12 K; monomethyl terephthalate, between 363.16 K and 381.51 K. From the variation of the vapor pressures with temperature, the standard molar enthalpies, entropies, and Gibbs energies of sublimation at T ) 298.15 K were calculated. The volatility of the studied compounds is compared with the volatilities of the benzene dicarboxylic acids and of the dimethyl benzenedicarboxylates.