An efficient cesium adsorbent has been developed using Prussian blue nanoparticles immobilized on cotton gauze. A cesium decontamination factor of the order of 10(6) is achieved by passing cesium solutions through a column filled with 1.81 g of the adsorbent. In this study, two ion-exchange steps were used, i.e., Na+ to K+ for immobilization of nanoparticles on matrices and K+ to Cs+ for adsorption. The new cesium adsorbent shows promise for the decontamination of radioactive cesium.