Results of Differential Scanning Calorimetry DSC experiments on homoionic montmorillonites(Ca²⁺,Mg²⁺,Na⁺,K⁺)and Na-kaolinite are reported.The low temperature exothermic peaks have been observed on cooling down to-90℃after initial peak corresponding to breakdown of supercooling of water in macro-and mezopores.In some experiments,the samples were then warmed to-10℃or-5℃and cooled again to-90℃.According to expectations,the non-equilibrium exothermic peaks were absent in this case,being replaced by a wide peak analogical to that obtained on warming.However,the low temperature exothermic peaks were still observed,but their fields were characteristically cut,proportionally to the extent of the earlier warming.The stochastic deconvolution applied to endothermic peaks obtained on warming allowed to compare the thermal effects corresponding to cooling and warming.The results unexpectedly give evidence that the portion of water,solidification of which can be attributed to the low temperature exothermic peaks,on warming melts in a wide temperature range and a separated melting point does not exist.Additional experiments by use of Modulated（MDSC）allowed to measure the apparent thermal capacity of the soil-water system down to-85℃.The results show that in temperatures corresponding to the low temperature exothermic peaks only a small portion of water undergoes phase change,and even at-85℃a significant amount of the adsorbed water remains unfrozen.