This work deals with the energetics of inter-and intramolecular hydrogen bonds in some phenolic derivatives. It shows that the calorimetric measurement of the enthalpy of sublimation (or vaporization) of these compounds contributes efficiently to determine energy values of this kind of bonds and to understand the crystalline structure of these compounds. Have been estimated, in kJ mol(-1), the enthalpies of : intermolecular hydrogen bonds : [H(O-H ... O=C) = 21, 2 et H(O-H ... O) = 14, 5] for the para-hydroxybenzoic acid, H(O-H ... O=N) = 14, 4 for the para-nitrophenol, [H(O-H ... N) = 27, 8 et H(N-H ... O) = 10, 7] for the para-aminophenol, H(O-H ... O) = 14, 5 for the para-dihydroxybenzene and H(O-H ... O) = 10, 2 for the para-and ortho-methylphenol isomers. intramolecular hydrogen bonds : H(O-H ... O=C) = 17, 8 for the ortho-hydroxybenzoic acid and H(O-H ... O=N) = 20, 1 for the ortho-nitrophenol.