A new process for converting coal fly ash to an artificial zeolite is described. The process is comprised of a high-temperature operation and water removal during the operation. Suitable operation parameters of the process were investigated using a test unit, and the optimal conditions were found to be 2.5-3.5 mol/dm(3) of NaOH and 0.88-1.10 dm(3)/kg of liquid/solid, sodium hydroxide charge from 2.2 to 3.9 mol/kg-CFA. The zeolites obtained from a pilot plant had a higher cation exchangeable capacity than those from the test unit and were comparable to zeolites prepared using a conventional method. (c) 2005 Elsevier Ltd. All rights reserved.