In this study, different variables that influence cesium adsorption from aqueous solutions were investigated by a synthesized nanocomposite. The synthesized spherical mesoporous silica surfaces were modified with potassium hexacyanoferrate and characterized by various methods such as FT-IR, XRD, FESEM, TGA and BET/BJH. The response surface methodology based on Central Composite Design was applied to optimize the cesium ion adsorption conditions, including the effects of initial cesium concentration, contact time, temperature and pH. Langmuir, Freundlich, and Temkin isotherm models analyzed the equilibrium concentration data. The isotherm studies indicated that the Langmuir model provides the best correlation of the experimental data. Based on the kinetic studies, the Blanchards model fits well with experimental data. The initial concentration and pH were the most influential factors on cesium adsorption. According to the obtained results, it can be concluded that the nanocomposite adsorbed cesium ions selectively even in the presence of high Na+, K+, and Sr2+ ions.