Hydration/dehydration behavior of polyalcoholic compounds with a rigid cyclohexane-type aliphatic molecular frame, such as 1,4-cyclohexanediol (ch(OH)(2)), 1a,3a,5a-cyclohexanetriol (cis-phloroglucitol, ch(OH)(3)), and cis-1,2,3,5-trans-4,6-cyclohexanehexaol (myo-inositol, ch(OH)6) was investigated using extremely high-frequency dielectric relaxation measurements up to 50 GHz over a temperature range from 10 to 70 degrees C. The temperature dependencies of hydration numbers per hydroxy group (m(oH)) in the polyalcoholic compounds were determined. Although the obtained moH value was ca. 5 in a temperature range lower than 30 C, it decreased and approached to ca. 3 with increasing temperature for ch(OH)(2) and ch(OH)(3), in which hydroxy groups hardly form intramolecular hydrogen bonds due to separations between them. This temperature-dependent hydration/dehydration behavior is characteristic of isolated hydroxy groups without intramolecular hydrogen bond formation. On the other hand, a constant moH value of ca. 1 was observed irrespective of temperature for ch(01-)(6). Because all the separations between adjacent hydroxy groups in ch(OH)(6) are proper for (circular type) intramolecular hydrogen bond formation, the obtained temperature-independent small moH value resulted from an inherent feature of intramolecularly hydrogen bonded hydroxy groups.