Liquid water is not stable on Mars surfaces due to low temperature and pressure conditions, but it may potentially be formed and stabilized through deliquescence of salts in the subsurface [1, 2]. Our preliminary findings suggest that the presence of hygroscopic divalent salts (e.g., CaCl2, MgCl2) enhances thewater sorption of nontronite, even at low water vapor pressures at 25 °C. Additionally, our Raman results revealed that nontronite in CaCl2 solution retained briny water better than other nontronite-salt mixtures (e.g.,NaCl, MgCl2) at -100 °C. This study revealed the complex roles of nontronite and various salts ability to form and retain briny water in an extended temperature range (-100 to 25 °C). It also offers essential insights to the aqueous (geo)chemical history of Mars and the search for potential water resources for future human explorations to Mars.