Grain processing operations often require the grain to absorb water. Different water absorption models (the Peleg model, the extended Peleg model, the Thakur model, and the Becker model) were adapted to the measured data of wheat, rye, barley, oats, rice, and maize. The best results were obtained for all cereal genera with the extended Peleg model with four parameters. The results obtained can help to create simulations of water absorption processes and simplify both monitoring and control of water absorption processes.