ABSTRACT The behavior of soluble uranium (VI) on the adsorption/desorption processes in the presence of a natural forest soil (FS) or a gamma-irradiated forest soil (FS-I) provides important knowledge on the fate and mobility of this element in contaminated soils and groundwater. Soil from a forest was irradiated with a dose of 1 MGy 60Co gamma radiation and was compared with natural soil to determine the behavior of U(VI) in these materials. Both natural and gamma irradiated soils were characterized by several physicochemical techniques. Kinetics, isotherms, effects of pH, U(VI) concentration, temperature, and stability of the U(VI)/adsorbents were considered. The equilibrium of adsorption processes U O 2 2 + /FS and U O 2 2 + /FS-I were achieved in 2 h, and the data were well fitted to the pseudo first (FS-I), pseudo second (FS), and Elovich models (FS): qe value was 14 mg g−1 for FS, slightly higher than 12 mg g−1 for FS-I. The isotherm data were well-fitted to the Langmuir and Temkin models for FS and FS-I, respectively. The processes of both materials are independent of the temperature between 30 and 50°C; however, they are sensitive to pH and U(VI) concentration. Furthermore, acidic media and complexing agents were good desorbents for U(VI) from the natural and irradiated soils.