The energy of combustion of cyclopentadecanone has been determined using a static bomb calorimeter. The vapour pressure of the compound was measured over a temperature interval of 18 K, by the Knudsen-effusion technique. Heat capacity measurements between T = 270 K and T = 335 K were carried out by d.s.c. From the experimental results of this work, the standard molar enthalpies of combustion, sublimation, and formation in the crystalline and gaseous state at the temperature 298.15 K, have been derived for cyclopentadecanone: ΔfH0m (cr) = -(501.4 ± 5.5) kJ · mol-1, ΔsubH0m = (86.0 ± 0.6) kJ · mol-1, ΔfH0m(g) = -(415.4 ± 5.5) kJ · mol-1, respectively. © 1997 Academic Press Limited.