In this work, hydrotalcites were used to remove131I− from aqueous solutions. It was found that131I− sorption by hydrotalcites depends greatly on the thermal treatment of the solid and does not take place by ion exchange as I− is not capable of removing CO 3 −2 or other ions in the hydrotalcite. The anions have to be removed from the solid in order to permit I− to be sorbed in the hydrotalcite. The radionuclide content was determined by γ-spectrometry and X-ray diffraction was used to identify the compounds and to estimate cell parameters.