The enthalpies of combustion and of sublimation, respectively, of the three isomeric nitrobenzonitriles have been measured: o-, {(-3456.3 ± 2.9), (88.1 ± 1.4)} kJ · mol-1; m-, {(-3442.8 ± 3.3), (92.8 ± 0.3)} kJ · mol-1; p-, {(-3448.2 ± 3.6), (91.1 ± 1.3)} kJ · mol-1. In turn, from these values, the standard molar enthalpies of formation for the condensed and gaseous state, respectively, have been derived: o-, {(130.1 ± 3.1), (218.2 ± 3.4)} kJ · mol-1; m-, {(116.5 ± 3.5), (209.3 ± 3.5)} kJ · mol-1; p-, {(122.0 ± 3.8), (213.1 ± 4.0)} kJ · mol-1. Destabilization energies associated with the presence of the two electron-withdrawing groups have been determined, for o-, m-, and p-nitrobenzonitrile, {(17.6 ± 4.1), (8.7 ± 4.2), and (12.5 ± 4.6)} kJ · mol-1, respectively, and are consistent with those obtained for the corresponding sets of isomeric methyl benzenedicarboxylates, dicyanobenzenes, dinitrobenzenes, and (neutral and ionized) nitrobenzoic acids.