The adsorption of uranium (VI) from aqueous solutions onto natural sepiolite has been studied using a batch adsorber. The parameters that affect the uranium (VI) sorption, Such as contact time, solution pH, initial uranium(VI) concentration, and temperature, have been investigated and optimized conditions determined. Equilibrium isotherm studies were used to evaluate the maximum sorption capacity of sepiolite and experimental results showed this to be 34.61 mg.g(-1). The experimental results were correlated reasonably well by the Langmuir adsorption isotherm and the isotherm parameters (Q(0) and b) were calculated. Thermodynamic parameters (Delta H degrees = -126.64 kJ . mol(-1), Delta S degrees = -353.84J . mol(-1) . K-1, Delta G degrees = -21.14 kJ . mol(-1)) showed the exothermic beat of adsorption and the feasibility of the process. The results suggested that sepiolite was suitable as sorbent material for recovery and adsorption of uranium (VI) ions from aqueous solutions. (C) 2009 Elsevier Ltd. All rights reserved.