A general method of converting various coal ashes into zeolites was investigated. Fly ashes from several utility power plants were fused with sodium hydroxide at 550 degrees C followed by dissolution in water and hydrothermal treatment. It was found that the solutions of fused powders can be cured at 60 degrees C under ambient pressure to precipitate faujasites. Atomic absorption spectroscopy of supernatant of solutions cured for various amounts of time showed that the concentration of Al species in the solutions has a dominant effect on the precipitation of faujasites. The fused ash solution that contained a higher amount of Al in the supernatant amount of faujasite. The ion-exchange capabilities of the converted faujasites with respect to Cs+ ions were measured. It was found that a higher yield of faujasites gives rise to a higher ion-exchange capability. SEM-EDXS indicated that, in addition to ion exchange, precipitation of a cesium compound in solution also occurred. Moreover, the supernatant of the fused powder solution can produce purer zeolites, and the sediments can be reused to generate solution for further precipitation of zeolites.