A flow-mixing calorimeter has been used to measure the excess molar enthalpy H-m(E) of (cyclohelane + dioxane)(g) and (benzene + dioxane)(g) at standard atmospheric pressure over the temperature range (373.2 to 423.2) K. The non-ideality of the cyclohexane, benzene, and dioxane was fitted using the Kihara potential, and cross-terms were calculated using the equation epsilon(12) = (1 -k(12))(epsilon(11)epsilon(22))(1/2). TO fit the measurements on (cyctohexane + dioxane)(g) the value (1 - k(12)) = 0.868 was needed. This value was used to calculate H-m(E) for (benzene + dioxane)(g), but the experimental values were found to be about 20 J.mol(-1) less positive. The difference between the calculated and experimental values was described in terms of a quasi-chemical model which, for the benzene-dioxane interaction, yielded a value of the equilibrium constant K-12(298.15 K) = 0.251 MPa-1 and an enthalpy of association Delta H-12 = -(11.6 +/- 3) kJ.mol(-1). This value of Delta H-12 is attributed to quadrupole-quadrupole coupling between benzene and dioxane which is much stronger than for the cyctohexane-dioxane interaction.