This study presents characteristics of sorption properties of croutons contained in instant soups. The sorption phenomenon was measured by means of static method analysing the water vapour adsorption isotherm and dynamic method by determining the water vapour adsorption kinetics and the process speed. The initial water content in the material was determined by means of thermal drying in 105°C. The adsorption isotherms were determined within the water activity a_w=0.07-0.98. The isotherms were subjected to the BET transformation within a_w=0.07-0.44 water activity, the monomolecular layer capacity Vm was calculated and the respective water activity and also the adsorption surface proper was determined. The water vapour adsorption isotherms in the products under study corresponded to Type II of the Brunauer classification. Croutons A had greater capacity of the monolayers and the adsorption surface proper; the obtained data may indicate those products’ being prone to the rehydration process. The water vapour adsorption kinetics curves was up to the environment water activity and the initial water content in the material under study. The sorption speed in the products under study was the greatest during the first 2 hours of the measurement taking (120 minutes). The water vapour adsorption speed dropped in the environment with water activity a_w=0.55-0.98, along with an increase in water content in the products under study.