Molar excess enthalpies H-m(E) have been measured at 298.15 K for binary mixtures (1,3-dioxane or 1,4-dioxane + cyclohexane or n-pentane or 2,2,4-trimethylpentane or tetrachloroethene or benzene) by using a home-made flow calorimeter constructed newly for determining excess enthalpy in the dilute concentration range. The positive H-m(E) for alkane and cycloalkane systems were found. Those of the benzene systems were exothermic except for the 1,4-dioxane rich region. The experimental result was discussed qualitatively in view of intermolecular interactions in mixtures and the isomer effect on thermodynamic properties of dioxane mixtures.