Abstract: The sorption isotherms of "beta" lactose, sodium bicarbonate and new water absorbent in powdered form were determined within the range of 11-100% relative humidity at 4�C, using saturated salt solutions method. The comparison between the sorption isotherms of "beta" lactose, sodium bicarbonate and new generation of water absorbent is studied. The new water absorbent was the most hygroscopic and had sigmoid shaped, type II isotherms according to Brunauer-Emmet-Teller (BET) classification. The "beta" lactose and sodium bicarbonate exhibited type III behaviour. The goodness of fit of the GAB model to experimental results was determined. All of the products tested, the new water absorbent gave good fit while the "beta" lactose and the sodium bicarbonate gave a less good fit.