Thermodynamic characteristic of micronized silica-water vapor working pair is essential for the designing and the sizing of solid desiccant dehumidification systems that incorporate a finned tube heat exchanger, where silica powder is coated on the surface of the fins for enhanced heat and mass transfer between adsorbent and humid air. In this work, the adsorption characteristics of water vapor onto various commercially available micronized silica powders, namely, Fuji-RD, S-Chemtech SIL54 and SIL120, are experimentally investigated and analyzed at temperatures from 25°C to 80°C at different equilibrium relative humidity between 0.03 and 0.95. A gravimetric technique is used to measure the mass change rate at the equilibrium state. Results reveal that the uptake capacity of SIL54 is two times other two silica gels under the operating conditions of a typical desiccant dehumidifier.