Enthalpies of dilution at 298.15 K of aqueous solutions of THF and 1,4-dioxane have been determined using flow microcalorimetry. The results obtained were used to determine the homotactic enthalpic interaction coefficients that characterize pair interactions of THF and 1,4-dioxane in aqueous solution. These are briefly discussed from the point of view of intermolecular interaction between the hydrated solute species.