A flow microcalorimeter of the Picker design was used to measure excess molar enthalpies H(E) at 298.15 K, as a function of the mole fraction x1 of the binary liquid mixtures cycloheptane (c-C7H14) + benzene (C6H6) or toluene (C6H5CH3) or ethylbenzene (C6H5C2H5), and cyclooctane (c-C8H16) + benzene or toluene or ethylbenzene. The calorimeter was equipped with separators and operated in the discontinuous mode. In each series, H(E) is largest for the mixture with benzene, and smallest for the mixture with ethylbenzene. For instance at x1 = 0.5, H(E)/J mol-1 is 821 for c-C7H14 + C6H6, 624 for c-C7H14 + C6H5CH3, and 548 for c-C7H14 + C6H5C2H5. For any given aromatic component, H(E) of the mixture with cycloheptane is slightly larger than H(E) of the corresponding mixture with cyclooctane. The results are discussed in terms of the simplest version of the KGB theory.