Swelling pressure of wetted grain was measured in a model silo. Experimental set was designed to simulate the conditions under which grain is subjected to wetting by ambient air of the humidity higher than the equilibrium relative humidity corresponding to the existing moisture content of grain. The model involves super- position of two basic kernel reactions to water supply: (i) swelling of kernels, (ii) decrease in kernels elasticity with an increase in the moisture content. The model properly describes the relation between swelling pressure and the increase in the moisture content in a range of the moisture content increase up to 0.02. Swelling pressure of the wetted grain is strongly influenced by the initial bulk density which depends on the precompression history. The experiments performed indicate that distribution and value of the swel- ling pressure in the model silo is not uniform and depends on the path of wet air movement.