The objective of this work was to study the sorption of uranium (VI) ions on magnesium oxide (MgO) from aqueous solutions. The MgO has been prepared via hydroxide precipitation followed by thermal decomposition of the hydroxide. MgO was characterized by X-ray powder diffraction, scanning electron microscope, and multipoint Brunauer, Emmett, and Teller. The relative importance of test parameters such concentration of adsorbate, pH, contact time, and temperature on adsorption performance of MgO for U(VI) ion were studied and the optimum sorption efficiency was found as 87.61 ± 3.10%. Desorption tests were also carried out and desorption efficiency was found as 100% with NH 4Cl and NaNO 3 solutions containing 0.1 M on a single step. Typical sorption isotherms (Freundlich and Dubinin-Raduskevich) were determined for the mechanism of sorption process and thermodynamic constants (δH°, δS°, and δG°) were calculated as -8.738 kJ mol -1, -21.68 kJ mol -1, and 0.102 kJ mol -1 K -1, respectively. Copyright © 2011 American Institute of Chemical Engineers (AIChE).