Copper hexacyanoferrate (CuHCF) with the composition of K0.76Cu[Fe(CN)(6)](0.69)center dot 3.6H(2)O was prepared and studied for its potential on recovering dissolved ammonia. Fast adsorption kinetics and the least impact of coexisting sodium ion, which is abundant in environmental waters, are noteworthy. From the solution of ammonium chloride in pure water, the material showed almost constant adsorption in the pH range of 2 to 7, a slight increment was observed until pH 9, and a decreasing tendency was observed afterward. This is because of the decreasing concentration of ammonium ion starting at pH 8. Interestingly, FT-IR taken after adsorption at pH 11 showed peaks of both ammonium and ammonia forms, which reinforces the applicability of the material for not only the ammonium ion but also the overall ammonia in solution phase. Results show potassium ammonium ion exchange as the major process behind the selective adsorption of ammonium. However, the mechanism of adsorption of the NH3 form is yet to be known. CuHCF holds an impressive ammonium adsorption capacity of 1.94 mol/kg in pure water solution. As high as 95% adsorbed ion could be desorbed with 1 mol/L potassium solution. Regeneration of the material was confirmed by comparing the XRD profiles. As per the observed equilibrium, potassium-ammonium ion exchange is a reversible process.