Starches originated from maize, wheat and potato were mixed sep. with glycerol (20% by mass) and then granulated with variable speed of extruder screw (60-120 rpm) at 70-120 degrees C. Measurements of water activity of the granules were performed immediately after the granulation and after 20, 40 and 60 days long storage in tight containers. All the granules showed low values of water activity. It decreased with increasing the screw speed. The storage of granules resulted in the growth of water activity. Addnl., sorption isotherms were detd. by using BET and GAB models.