The thermodynamic property surfaces of silica gel + water systems have been developed and described from the rigor of chemical equilibria between adsorbed and gaseous phases, Maxwell relations, the entropy of the adsorbed phase, and experimentally measured adsorption isotherm data. These property fields compute the entropy, enthalpy, specific heat capacity, and isosteric heat of adsorption as a function of pressure, temperature, and the amount of adsorbate thoroughly, which are essential for calculating the energetic performances of adsorption cooling and desalination processes. In this paper, the properties of enthalpy and entropy data for the silica gel + water system at temperatures from (273 to 373) K and at different equilibrium pressures between (0.5 and 10) kPa are furnished. The specific heat capacity and the isosteric heat of adsorption obtained by the proposed property fields are also compared with experimental data.