LR gas-phase and quantum chemical data that characterize the intramolecular hydrogen bonds in a series of 2-hydroxybenzoyl compounds (Ph(OH)(COY) : Y = Cl, OH, SH, OCH3, SCH3, H, CH3, Ph, N(CH(CH3)CH2)(2)CH2, N(CH2CH2)(2)CH2, N(CH3)(2), NHCH3, NH2, NHNH2) are reported and discussed. The sequences of nu(OH) and of nu(CO) frequencies calculated at HF/3-21G, HF/6-31G**, and B3LYP/6-31G** computational levels agree reasonably well with the corresponding experimental sequences. The consistency of the calculated data is demonstrated by exploiting several relations between calculated frequencies, force constants, and bond distances. It is shown that the sequence of hydrogen bond strengths, as defined either by nu(OH) frequency shifts or by R(O-H) bond distances, may qualitatively be interpreted in terms of two quantities, the R(H ... O) hydrogen bond distances and the Q(O) oxygen partial charges, which characterize the intrinsic differences between the carbonyl groups.