Abstract: A method for removal of cesium from aqueous solution, particularly from nuclear waste liquids. The cesium-containing aqueous solution is contacted with a solid-state hexacyanoferrate compound of a transition element for binding cesium to the hexacyanoferrate. The aqueous solution of reduced cesium content is separated from the hexacyanoferrate. Preferably, a nickel or cobalt hexacyanoferrate is utilized having a fraction of exchangeable transition elements smaller than 35 %. The hexacyanoferrate compound of said transition element may be produced by slowly adding an aqueous solution of the hexacyanoferrate into the transition element salt solution, the concentration of the transition element salt solution being at least 0.35 mol/l, stirring the mixture at ambient temperature during the addition, and separating and recovering the resulting hexacyanoferrate precipitate from the mixture.