Heats of mixing and densities of very dilute aqueous solutions (mol) fraction concentration < 2 × 10–3 of cyclic ether derivatives have been measured at several temperatures. The solutions studied included tetrahydrofuran, tetrahydropyran, 1,4-dioxan, tetrahydrofurfuryl alcohol, and tetrahydropyran-2-carbinol. Limiting partial heats, heat capacities, volumes and expansibilities are discussed in terms of current ideas on polar and apolar hydration.