Co-60(2+) ion exchange at room temperature (20 degrees C) from aqueous cobalt chloride solution with zeolite NaA either hydrated or heated at 150 and 600 degrees C has been studied, In all samples a fast Co2+ uptake is found in which 2 meg Na+ ions/g of zeolite are replaced by cobalt ions. This process is stable and no desorption is observed, These results are quite different from those obtained in previous work with zeolite NaY which showed that sorption was followed by a desorption process.