Mesoporous smectite-type clays containing different metals, such as Mg, Fe, Co, or Ni, were synthesized by a hydrothermal method and tested for reforming of methane with carbon dioxide. The synthesized clays had smectite-type structure with mesopores and high surface areas. After hydrogen reduction, the synthesized smectite materials containing Ni are highly active for the reforming reaction. Their activity depends on the synthetic conditions used. The smectite materials prepared at lower slurry pH values and lower hydrothermal temperatures exhibit higher activity than a reference catalyst of Ni/SiO2 prepared by impregnation method. The most active Ni-containing smectite catalyst is superior to the conventional supported Ni catalysts reported in the literature. The turnover frequency (TOF) of Ni smectite catalysts significantly depends on the size of Ni crystallites, which are formed on the reduction; those having smaller Ni crystallites show higher TOF values. (c) 2006 Elsevier B.V. All rights reserved.