Ce0.75Zr0.25O2 solid solution supported Ru catalysts were prepared and tested for CH4-CO2 reforming. The effect of Ru content on the properties of the catalysts was investigated by means of N-2 adsorption-desorption, H-2-TPR/MS, XRD, XPS, CO chernisorption and H-2-TPD/MS. It was found that the highly dispersed Ru species favored the interaction between Ru and Ce0.75Zr0.25O2. The reduced Ce0.75Zr0.25O2 was able to store hydrogen, while Ru promoted the reduction of Ce0.75Zr0.25O2. Under the identical conditions, the CH4 and CO2 conversions of the catalysts increased with the increase of Ru content, however, the turnover frequencies of CH4 and CO2 were higher for the catalysts with lower Ru contents, which may be resulted from the strong interaction between Ru and Ce0.75Zr0.25O2. The Ru catalyst exhibited good stability and excellent resistance to carbon deposition. Remarkably, zirconium and cerium hydrides were detected in the used catalyst, which may participate in the elimination of the carbon deposit. Apart from the nature of metallic Ru and the redox property of Ce0.75Zr0.25O2, we suggest that the excellent resistance of the catalyst to carbon deposition is also attributed to the hydrogen storage of the reduced Ce0.75Zr0.25O2. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.