Water clusters of Na+, K+, and NH4 + ions with Cl- and I- counterions are studied using 17O NMR spectroscopy. It is found that, in the range of electrolyte concentrations 0.001-5 mol/l, the concentration dependence of the spin-spin relaxation time of oxygen nuclei in water molecules varies widely, depending on the nature of the cation. The influence of the electrolyte concentration on the chemical shifts and relaxation times of 17O nuclei is analyzed. A qualitative explanation of the results obtained is suggested. Copyright © 2005 by Pleiades Publishing, Inc.