A new test rig for measuring the adsorption equilibrium of water on silica gel has been developed. The adsorption equilibrium of water on silica gel was then measured using the weight method. The measured temperature ranged from (25 to 90) degrees C, and the absolute pressure was in the range of (300 to 20 000) Pa. The water uptake of silica gel varied :from (0.03 to 0.30) kg.kg(-1). Data obtained were fitted to three equations: the Dubinin-Astakhov (DA) equation, the Freundlich equation, and the modified Freundlich equation. The modified Freundlich equation showed the best agreement with the experimental data, while the DA equation and Freundlich equation had a large deviation with the experimental data for low water uptake.