The Knudsen mass-loss effusion technique was used to measure the vapour pressures at different temperatures of the following crystalline compounds: 1,2-diphenylethane (bibenzyl), between T = 289.16 K and T = 303.20 K, and of 3-phenylpropiolic acid between T = 329.15 K and T = 343.15 K. From the temperature dependence of the vapour pressure, the standard molar enthalpies of sublimation at the mean temperature of the experimental range were derived by the Clausius-Clapeyron equation. From these results the standard, p degrees = 10(5) Pa, molar enthalpies, entropies, and Gibbs energies of sublimation at T = 298.15 K, were calculated: [GRAPHICS]