Newly synthesized mesoporous zirconia-based catalysts were investigated for the WGS reaction, using niobium oxide as a promoter and platinum as the active metal. Their performances for hydrogen production were correlated to the surface properties. Niobium addition gives rise to different effects: the 0.3 loading considerably enhances the catalytic performances of the catalyst for all temperatures, for both hydrogen production and selectivity (with respect to the CO to CO2 oxidation). On the contrary, when a Nb monolayer is produced on the zirconia surface, the activity is highly reduced with respect to the Pt/ZrO2 sample. In particular, the acid–base behaviour of the surface was linked to the zirconia–niobia interaction and its consequence on the metal–support interaction. A description of the surface was attempted and a reaction pathway through formate species formation and decomposition proposed.