Thermal oscillations of solubility, showing as nonmonotonic segments of the solubility curve of nitratine, NaNO3 (R (3) over barc), bearing maxima, minima, or salient points, have been revealed in the NaNO3-H2O system as a result of three series of experiments (more than 170 tests altogether). The oscillation appeared in narrow ranges of the salt component concentration (less than 10% by weight) and reached 4-10degreesC, being accompanied by sudden alterations of pH values (up to I of pH unit). The second salt phase of NaNO3, which seemed to have eutoic point with nitratine at 31.6degreesC, was discovered. Relationship between structural changes in the liquid and crystalline phases and kinetic anomalies of crystal growth in the solutions are also discussed here. (C) 2003 Elsevier Science B.V. All rights reserved.