Vapour pressures as functions of temperature of seven crystalline copper(II) beta-diketonates, CuL(2), were measured using either the Knudsen mass-loss effusion technique (Oporto apparatus), the simultaneous torsion and mass-loss effusion technique (Utrecht apparatus), or both. From the temperature dependence of the vapour pressure, the standard molar enthalpies of sublimation, at the mean temperature of the experimental temperature range, Delta(cr)(g) H-m degrees ((T)), were derived, and the standard molar enthalpies of sublimation, at the temperature 298.15 K, were calculated : [GRAPHICS] where HACAC, pentane-2,4-dione; HPIPRM, 2,2-dimethylheptane-3,5-dione; HDIBM, 2,6-dimethylheptane-3,5-dione; HIBPM, 2,2, 6-trimethylheptane-3,5-dione; HDPM, 2,2,6,6-tetramethylheptane-3,5-dione; HBZAC, 1-phenylbutane-1,3-dione; and HTFAC, 1,1,1-trifluoropentane-2,4-dione. The consistency of the vapour-pressure measurements was tested by measuring the vapour pressures of benzoic acid, at various temperatures, by different experimental techniques : Knudsen mass-loss effusion, simultaneous torsion and mass-loss effusion technique, and spinning rotor. From the standard molar enthalpies of formation of the gaseous complexes, the mean molar (Cu-O) bond-dissociation enthalpies were derived.