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Hydrationphenomena play a very important role in various processes,in particular in biological systems. Water molecules in aqueous solutionsof organic compounds can be distributed among the following substructures:(i) hydration shells of hydrophilic functional groups of molecules,(ii) water in the environment of nonpolar moieties, and (iii) bulkwater. Up to now, the values of hydration parameters suggested forthe description of various solutions of organic compounds were notthoroughly analyzed in the aspect of the consideration of the totalmolecular composition. The temperature and concentration dependencesof relaxation rates of water deuterons were studied in a wide rangeof concentration and temperature in aqueous (D2O) solutionsof a set of ω-amino acids. Assuming the coordination numberof the CH2group equal to 7, which was determined fromquantum-chemical calculations, it was found that the rotational correlationtimes of water molecules near the methylene group is 1.5–2times greater than one for pure water. The average rotational mobilityof water molecules in the hydration shells of hydrophilic groups ofω-amino acids is a bit slower than that in pure solvent at temperatureshigher that 60 °C, but at lower temperatures, it is 0.8–1.0of values of correlation times for bulk water. The technique suggestedprovides the basis for the characterization of different hydrophobicand hydrophilic species in the convenient terms of the rotationalcorrelation times for the nearest water molecules. [ABSTRACT FROM AUTHOR]