The dependence of the mesoporous structure (mp) on the catalytic performance of Ni/CeO2-mp and Ni/CeO2-La2O3-mp was evaluated for high-quality mesoporous materials prepared from an SBA-15 template. The samples were characterized by different analytical techniques followed by the catalytic evaluation in a fixed bed reactor (GHSV 36,000 h-1). From these results, ceria-mesoporous samples (CeO2-mp) showed a highly ordered pore system with assemblies of slit-shaped mesopores, and a moderate improvement in CO2 conversion to CH4 due to the presence of basic sites for the Ni/CeO2-La2O3-mp. Subsequently, the influence of the mp-structure on their reactivity was investigated by evaluating the Ni0 and Ni2+-CeO2 active sites for CO2 methanation from in-situ NAP-XPS experiments as a function of both chemical environment (CO2 / H2) and operating temperature (up to 350 °C). The results highlighted the critical role of mesopores in maintaining the proper balance of the active species (Ni0/Ni2+-CeO2 ~ 2.5) that are present on the catalyst surface, leading to enhanced reactivity over a wide range of operating temperatures (250-350 °C) compared to conventional ceria supports. Furthermore, it has been demonstrated that this spectroscopic technique provides valuable insights into the concave surface behavior for monitoring reactivity on mesoporous catalysts, allowing us to contribute to the advancement of methanation reaction technology using CO2.