This paper studies the water equilibrium uptake on two lype of adsorbents, namely silica gel RD powder and Zeolite FAM Z01. A novel adsorption isotherm model is proposed to regress the experimental data of the both adsorbents. For the silica gel-water pair, die proposed model generates more precise data regression than the classic DA and Tóth equations. In the case of the zeolite-water pair, the new model well fits its unique S-shape isotherms at various adsorption temperatures. The linear behavior at both low and high relative pressure regions, and the sharp rise in between the two regions arc accurately captured. The model produces R2value 0.997 and NRMSE error 3.15% for the former pair, and 0.997 R2and 6.05% error for the zeolite-water pair in the experiment range.