The standard (p(o) = 0.1 MPa) molar enthalpies of combustion, Delta(c)H(m)(o), for crystalline 2-, 4-, 6-chloroquinoline and 4.7-dichloroniquinoline were determined at the temperature 298.15 K using a rotating-bomb combustion calorimeter. The standard molar enthalpies of sublimation, Delta(cr)(g)H(m)(o) at T = 298.15 K, were determined by Calvet microcalorimetry. The results were as follows: [GRAPHICS] These values were used to derive the standard molar enthalpies of formation of the compounds in their crystalline and gaseous phases, respectively. The derived standard molar enthalpies of formation, in the gaseous state, are analysed in terms of enthalpic increments and interpreted in terms of molecular structure. (c) 2005 Elsevier Ltd. All rights reserved.