Abstract The dilatometric properties of W1 W2, and W3, which were proposed by the present authors, for the classification of water in macromolecular gels, are studied over the range from −30 to 60°C. From the results of the thermal expansion of agarose gels and Sephadex (cross-linked dextrans), higher water contents of gel were found to show an extremely sharp volume change at 0°C; on the contrary, lower water contents of gel exhibited no anomalous change in the specific volume in the range from −30 to 0°C, and a gradual decrease in the specific volume was detected with an increase in the temperature in the range from −20 to 0°C for medium water contents of the gel, though the gel was expected to increase in its volume in that temperature range. Thus, the new classification for the states of water in macromolecular gels was shown to be reasonable, at the same time, the transition temperatures of W1 W2, and W3 were evaluated on the basis of the above results. The thermal expansion of water in macromolecular gels, even of W1 was found to be extremely depressed by the polymers of such gels.