CO x hydrogenation reactions for hydrocarbon synthesis, such as methane, are becoming more and more important in terms of the energy transition. The formation of the byproduct water leads to a hydrothermal environment, which necessitates stable catalyst materials under harsh reaction conditions. Therefore, novel nanostructured core-shell catalysts are part of scientific discussion, since these materials offer an exceptional resistance against thermal sintering. Here we report on a core-shell catalyst -Co@mSiO 2 -for the hydrogenation of CO/CO 2 mixtures towards methane. CO methanation experiments reveal a rapid temperature-depended deactivation for temperatures above 350°C caused by coking and possible blocking of the pores. In comparison to a Co/mSiO 2 reference catalyst with the same Co particle size a significantly higher methane selectivity was found for CO 2 hydrogenation, which we attribute to the confinement effect of the core-shell structure and therefore a higher probability of CO readsorption. Finally, the simultaneous CO/ CO 2 co-methanation experiments show a high flexibility of the catalyst materials on different gas feed compositions.[a] J. Ilsemann, + Prof. Dr. M. Bäumer