The inorganic components of soil from a semiarid region were separated and characterized. Kinetics of adsorption of cesium and cobalt ions by the inorganic components of the soils behave according to the kinetic model of pseudo-second order, indicating that the adsorption process is chemisorption. Equilibriums were quickly reached in ca. 1 min, 98.6 +/- 0.5% of cesium and 96 +/- 1% of cobalt were retained in the solid from solutions. The sorption isotherm data, q(e) vs. C-e, were best adjusted to the Langmuir model. The adsorption capacities for cobalt and cesium are similar from pH 4 to 8 and at higher pH cobalt precipitates as hydroxide. Ionic strength plays an important role in adsorption; even low concentrations of sodium (<0.1 M) virtually avoid the adsorption for cesium and cobalt. The thermodynamic parameters indicated that the adsorption processes were exothermic for both cesium and cobalt by the inorganic materials of soil. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.