In this study, the performance of modified adsorbents obtained from activated carbon for the adsorption of thorium(IV) ions from aqueous media was investigated. The analytical and spectroscopic methods such as FT-IR, BET, SEM and UV-Vis were used to examine the properties of the modified materials. According to the analysis results, the both adsorbents had large surface areas after modification. Then, temperature, pH, mixing time and solution concentration parameters were observed to determine optimum thorium adsorption conditions on modified materials. The obtained results from the experiments were applied different three kinetic models and adsorption isotherms and thermodynamic parameters were calculated and then all of the results were interpreted. The adsorption process for both adsorption systems was observed to be compatible with the pseudo-second-order kinetic model. The adsorption equilibrium data were best described by the Langmuir model for modified adsorbent with KMnO4 and by the Freundlich model for modified adsorbent with NaOH. Furthermore, the calculated thermodynamic parameters (Delta G degrees, Delta H degrees and Delta S degrees) showed that the both adsorption processes were endothermic and spontaneous. The data show that modified adsorbents can be used as influential and low-cost adsorbents to remove thorium ion. Modified new adsorbents were highly selective for thorium ion in competitive adsorption studies.