The standard (p degrees = 0.1 MPa) molar enthalpies of formation, Delta H-f degrees(m), of crystalline 2-, 3- and 4-chlorobenzophenone and 4,4 '-dichlorobenzophenone were derived from the standard molar energies of combustion, Delta U-c degrees(m) in oxygen, to yield CO2(g), N-2(g), and HCl center dot 600H(2)O(l), at T = 298.15 K, measured by rotating bomb combustion calorimetry. The Calvet high-temperature vacuum sublimation technique was used to measure the enthalpy of sublimation, Delta(g)(cr) H degrees(m) of the compound 2-chlorobenzophenone. For the other three compounds, the standard molar enthalpies of sublimation, at T = 298.15 K were derived by the Clausius-Clapeyron equation, from the temperature dependence of the vapor pressures of these compounds, measured by the Knudsen-effusion technique. From the values of Delta H-f degrees(m) and Delta H-g(cr)degrees(m), the standard molar enthalpies of formation of all the compounds, in the gaseous phase, Delta H-f degrees(m)(g), at T = 298.15 K, were derived. These values were also calculated by using the B3LYP/6-311+G(2d,2p)//B3LYP/6-31G(d) computational approach.