Copper hexacyanoferrate(II) was incorporated in the matrix of the strongly basic anion-exchange resin Indion-810 for the sorption of radiocesium from aqueous solutions. Its efficiency for the removal of cesium was tested under both static and dynamic conditions. The resin was found to be highly selective for radiocesium from a variety of salt and acid solutions. With the help of x-ray diffraction patterns, infrared spectrometry, thermal gravimetry, and differential thermal analysis, the interaction of copper hexacyanoferrate(II) with the quaternary amine of Indion-810 resin was investigated. Pilot-scale studies using this resin indicated that radiocesium can be effectively removed from thousands of bed volumes of spent fuel storage bay water.