In this article, we have presented the studies regarding the improvements of the adsorption performance of a styrene-12% divinylbenzene copolymer functionalized with aminophosphonate groups in the removal process of thallium ions from aqueous solutions, by impregnation of the solid support with trihexyl(tetradecyl)phosphonium chloride (Cyphos IL-101). The use of ionic liquid impregnated polymer as adsorbent in the removal process of radionuclides presents higher adsorption performance because, in this case, the advantages of the ionic liquids are combined with the properties of the solid support. Until now the ionic liquids were intensive studied in the removal process of radionuclides from aqueous solutions but using the liquid-liquid extraction. In our case these are used in the solid-liquid separation process, a smaller quantity of ionic liquids being used (which decrease the cost of the adsorption process), and the loss of the ionic liquids in the aqueous phase being avoided. The ultrasonication method used for the impregnation of the ionic liquids onto the solid support is also a new and original one. The impregnation of the solid support with Cyphos IL-101 significantly increased its adsorption performance in the removal process of Tl(I) ions from aqueous solutions. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.