Ru/NaY and Ru/USY catalysts were prepared by ion exchange from an aqueous solution of [Ru(NH3)(6)]Cl-3. The effect of titanium on the structure of Ru/zeolite introduced by ion exchange or impregnation method from aqueous solution of (NH4)(2)TiO(C2O4)(2).H2O was investigated. The samples were characterized by different techniques, using X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), temperature-programmed desorption of hydrogen (TPD-H-2), Fourier transform infrared spectroscopy (FTIR) of CO adsorption and transmission electron microscopy (TEM). Introduction of titanium into Ru/NaY zeolite by ion exchange caused a significant structural collapse of the zeolite framework. Contrary to that, TEM data showed that Ti incorporated into Ru/USY by ion exchange was well distributed within the zeolite cavities. The crystallinity of the USY zeolite decreased significantly after introduction of Ti by impregnation method and a separate phase of titania was formed. The effect of Ti content on the catalytic behavior of zeolite-supported Ru. catalysts in the reaction of CO2 reforming of CH4 was elucidated. The higher specific activity of Ti-containing catalysts related to CO formation was caused by the both factors, the acceleration of CHxO decomposition (precursor for CO formation) on metal-support interface and participation of the reverse of water gas shift reaction. (C) 2002 Elsevier Science B.V. All rights reserved.