Carbon dioxide reforming of methane to synthesis gas has been investigated with Ni-supported clinoptilolite catalysts. The catalysts were prepared by using the incipient wetness impregnation method. The catalytic activity of Ni supported on clinoptilolite with varying Ni loadings was determined and the results showed that at 700 degrees C, 8 wt% Ni/clinoptilolite gave the highest activity. It exhibited not only the highest activity and selectivity but also remarkable stability. Moreover, both the activity and stability of this catalyst were observed to vary with the Zr content, exhibiting a maximum at a composition of 2% Zr. The amount of carbonaceous deposits on the spent catalysts was further investigated by temperature-programmed oxidation (TPO) and thermogravimetric analyzer (TGA) studies. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.