The aim of this study was to investigate the effect of natural zeolite addition on the sintering kinetics. Clinoptilolite which is a type of natural zeolite was added partially or fully in replacement of quartz at selected electro-porcelain composition. Samples were fired in an electric furnace with a heating rate of 10 degrees C/min at 1150, 1200 and 1250 degrees C with a period of 5, 10, 20, 30, 60 and 90 min. The sintered samples were characterized by XRD and SEM. Sintering activation energies were determined according to the bulk density results. It was found that the sintering activation energy decreased with increasing zeolite addition. (C) 2007 Elsevier B.V. All rights reserved.