AbstractAs a first step toward evaluating factors that influence humidity and heat transfer from moist air to dry air through porous media having very small pores, the present paper attempts to clarify factors that influence moisture transport between constant‐temperature water and dry air through a porous media plate. The effect of the pore diameter of the porous plate on the humidity transport through a porous plate was found to depend strongly on the thickness and pore diameter of the porous plate. That is, the smaller the pore diameter and the thicker the plate, the greater the effect of the pore diameter on the humidity transfer. In addition, the performance of heat and mass transfer were confirmed to increase with respect to the increase of air velocity. In addition, a parameter called the humidity absorption rate was introduced to evaluate the utilization degree of the air capacity to absorb humidity. The humidity absorption rate decreased with increases in both air velocity and plate thickness. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(2): 137–151, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20102