In order to analyze the treatment of seeds with homogeneous static magnetic field on the water adsorption process, an experimental-theoretical study of hygroscopic equilibrium in maize seeds (Zea mays L. cv. ICAV305) was carried out. Four treatments with magnetic induction of 80.0, 120.0, 160.0, and 200.0mT were applied for 10min, and there was a control group without treatment. The doses were selected because they showed a decrease in mean germination time. Treated seeds were subjected to an environment with a stable temperature of 30.0 degrees C +/- 0.1 degrees C and atmospheres of different relative humidity (h), using eight salt solutions saturated with water activity between 0.216 and 0.970. Curves were adjusted using the D'Arcy-Watt and modified Oswin models. It was found that the magnetic treatment of seeds affects adsorption, and the 200mT10min one was the most significant in affecting the mechanisms of adsorption of water, and increasing the number of adsorption sites connected to weak binds with D'Arcy-Watt's adjustment. Using the Oswin model for simulation, we verified that the magnetic stimulus affected the enthalpy of adsorption and the mechanism of incorporation of water vapor molecules to the structure of seminal cover. These results show that the magnetic pre-treatment of seeds has an effect on a seed's specific biophysical and physiological processes in the early stages of germination. Bioelectromagnetics. 39:343-351, 2018. (c) 2018 Wiley Periodicals, Inc.