Glycerol dry reforming (GDR) was studied on Ru/La2O3, Ru/ZrO2, and Ru/La2O3–ZrO2 catalysts. Impacts of the support on morphological, electronic and surface chemical properties of the catalysts were comprehensively characterized by TEM, in–situ DRIFTS, XPS, ATR–IR and XRD. Initial (5 h) CO2 conversion at 750 °C and CO2–to–glycerol ratio of 1–4 was ordered as Ru/La2O3 < Ru/ZrO2 < Ru/La2O3–ZrO2. During 72 h stability tests, Ru/ZrO2 deactivated by ~33% due to Ru sintering, structural deformation of the monoclinic zirconia support, and strong metal–support interaction. Under identical conditions, CO2 conversion on Ru/La2O3 decreased by 27% mainly due to dehydroxylation/carbonation of lanthana and severe coking. Lanthana–stabilized tetragonal zirconia phase of Ru/La2O3–ZrO2 led to finely dispersed small oxidic Ru clusters which deactivated by 15% after 72 h and demonstrated unusually high catalytic performance that was on par with the significantly more expensive Rh–based catalysts, which are known with their exceptional activity and stability in GDR.