A transition metal hexacyanoferrate product CsTreat has been utilized at industrial scale for radioactive cesium separation at several nuclear power plants (NPPs) in several countries. A granular hexacyanoferrate ion exchanger has been used in packed-bed column mode operations for the removal of cesium from a variety of wastewater types. CsTreat beds have successfully purified both high-salt evaporator concentrates and dilute floor drain waters at NPPs in Finland and the United States. Furthermore, medium-active reprocessing solutions, containing high concentrations of sodium nitrate, have been decontaminated by a CsTreat bed at the Japan Atomic Energy Research Institute. These solutions are described as are other industrial applications of this ion exchange material, which, of all the commercial materials, has been shown to be the most selective exchanger for cesium. In addition, some prospective fields of hexacyanoferrate utilization, such as the use of CsTreat powder in a precoat filtration system, are discussed.