Supercooling temperatures and enthalpies of mixing with some solvents have been examined for two kinds of solutions subjected to different thermal treatments (solutions I and II) of tetrahydrofuran (THF), isopropyl alcohol (2-PrOH), and ethyleneglycol butylether (BE), and ethyleneglycol isobutylether (i-BE) in order to observe more directly the structural organization of water molecules around a nonpolar molecule in an aqueous solution. For THF and 2-PrOH solutions, supercooling temperatures of solution I were found to be 2–3 degrees higher than those of solution II, and differences ΔHI-ΔHII were found to be about 3 kJ mol−1. It has been concluded that these results directly reflect the difference in the stability of hydrogen-bonded water networks in an aqueous solution.