The ammonium salt of heteropoly acid (NH(4)HPA) deposited on the surface of mesoporous silica (SBA-15) support was prepared and characterized using the following analytical techniques: X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscopy (SEM), particle size analysis and infrared spectra. The spectroscopic results revealed that the NH(4)HPA was well dispersed on the internal and external silica surfaces. The ion exchange capacity tests demonstrated that the insertion of the NH(4)HPA phase on the silica surface increased the specific activity for Cs removal. The ion exchange capacity of Cs increased with increasing the HPA loading. The NH(4)HPA at a loading of 50 wt% supported on silica showed a high ion exchange capacity (70.9 mg/g) for Cs ion. The effects of co-existing cations, nitric acid and temperature on the Cs sorption efficiency onto the composites were investigated. (C) 2013 Elsevier B.V. All rights reserved.