Nanoporous silicates MCM-41 have been prepared using different surfactants such as cetyltrimethylammonium bromide (C16TAB) and dodecyltrimethylammonium bromide (C12TAB) as template. The adsorbents are characterized using powder x-ray diffraction, nitrogen adsorption-desorption isotherm data, scanning electron microscopy, and transmission electron microscopy. The thorium sorption was studied as a function of shaking time, pH, initial concentration, and temperature. The sorption of thorium at the determined optimum conditions follows Langmuir and Freundlich isotherms. The results show that the nanoporous MCM-41 synthesized by C12TAB has more adsorption capacity than the MCM-41 synthesized by C16TAB (77.6 µmol · g−1 vs. 52.1 µmol · g−1) at 25°C. Th(IV) adsorption onto nanoporous adsorbents was very fast process and therefore, this adsorbent is suitable for column separation. Thermodynamic parameters such as ΔH°, ΔS° and ΔG° were found to be 47.76 KJ · mol−1, 196.21 J · mol−1 · K−1, and 19.00 KJ · mol−1, respectively (at 298 K). The positive value ΔH° suggested the endothermic nature of adsorption and negative ΔG° indicates the feasibility and spontaneity of the adsorption process.