We have carried out a study of the energetics, structural, and physical properties of o-, m-, and p-hydroxybenzophenone neutral molecules, C 13H10O2, and their corresponding anions. In particular, the standard enthalpies of formation in the gas phase at 298.15 K for all of these species were determined. A reliable experimental estimation of the enthalpy associated with intramolecular hydrogen bonding in chelated species was experimentally obtained. The gas-phase acidities (GA) of benzophenones, substituted phenols, and several aliphatic alcohols are compared with the corresponding aqueous acidities (pKa), covering a range of 278 kJmol?1 in GA and 11.4 in pKa. A computational study of the various species shed light on structural effects and further confirmed the self-consistency of the experimental results. © 2010 American Chemical Society.