In this study, infrared (IR) and differential thermal analysis (DTA) data were used to investigate the mobility of water adsorbed in synthetic zeolites of type 5A and 13X with pore diameters of 5 and 10 Angstrom, respectively. The results indicate that there are at least two types of water, mobile and immobile ones, in the narrow pore zeolite, while there is only mobile water in the wide pore zeolite.