Physical properties of gamma-irradiated soybeans were evaluated at different temperatures by determining water absorption pattern and cooking characteristics of the sample. Irradiation at 2.5–10 kGy caused the reduction of soaking time in soybeans by 2–5 hours and the increase of hydration capacity of 10–20%, respectively, compared to the non-irradiated control at 20°C. The activation energy for water absorption was lower in irradiated soybeans than in the non-irradiated control. Irradiation at 2.5–10 kGy caused the reduction of cooking time in soybeans by 30–60% compared to the non-irradiated control and the cooking rate constant of irradiated samples was higher about 2 times than that of the non-irradiated control. The irradiation efficacy on physical quality improvement was also recognized in the stored soybeans for one year at room temperature.