Excess molar enthalpies, H-E, for the binary mixtures of cyclopentanone, cyclohexanone, or cycloheptanone with n-nonane were measured at T = 298.15 K and 0.1 MPa, by means of a Setaram Tian-Calvet MS80 microcalorimeter. All the binary systems investigated show endothermic behaviour (positive values) over the whole mole fraction range. The molar excess enthalpies decrease as the size of the cycloalkanone increases. The experimental results of H-E are fitted to the Redlich-Kister equation to correlate the composition dependence. The experimental H-E data are also used to test the suitability of the Wilson, NRTL, and UNIQUAC models. The correlation of excess enthalpy data in these binary systems using the UNIQUAC model provides relatively the most appropriate results. (C) 2014 Elsevier Ltd. All rights reserved.