High-level moisture removal is often encountered in the pressure swing adsorption (PSA) for air prepurification. The effects of high-concentration water vapor adsorption on the heat and mass transport characteristics of PSA should be described in detail for further design and optimization of air prepurification processes. In this work, a mathematical model of an alumina/13X-layered two-bed Skarstrom-type PSA cycle for the removal of high-level moisture along with CO2 from air is established to study the heat and mass transport characteristics during the process. The maximum increase and decrease in temperature are related to the water vapor concentration in the feed air, and two simplified formulas are proposed to estimate their magnitudes. The mass transport characteristics, especially the penetration depths of the two impurities, are examined under different inlet temperatures, adsorption pressures, purge-to-adsorption flow rate ratios, inlet flow rates, and cycle times. A relation between the penetration depth of water vapor and the five operating parameters is developed and can be readily used to predict the location of the water vapor adsorption front in the PSA design for air prepurification and other purification processes involving high-level moisture.