Physicochemical properties of water films formed on the surfaces of porous silicas were studied by high-resolution thermogravimetry (TGA) and differential scanning calorimetry (DSC) over a temperature range from -70 degrees C to 250 degrees C, Silica samples were exposed to water under different conditions in order to prepare surface films of variable thickness. It was shown that TGA and DSC measurements are useful for investigating the physicochemical properties of surface water films and the sorption properties of silica supports.