In the process of incorporating adsorption with thermal desalination, adsorbents are important because they increase the water vapour uptake rate, and this would yield more desalinated water over a short period. Therefore, they are important and the key parameters in the selection of adsorbent for an adsorption desalination (AD) cycle are thermo-physical properties, surface characteristics and water vapor uptake capacity. The best adsorbent is used as the adsorbent-refrigerant pair and is driven at 50 oC to 85 oC by low-temperature heat sources. When the unsaturated adsorbent is exposed to vapour in the evaporator, the uptake of vapor is accelerated by the high affinity of the water molecules to the silica gel pores. Likewise, when the same adsorbent is heated thermally, the water vapor molecules are removed or desorbed from the adsorbent pores to the cooler surfaces of the condenser tubes, producing high-grade water during the phase. Key words: Desalination; Porosity; Adsorption isotherm; Geometric parameters. Sorption Phenomenon