A series of γ-LiAlO2-Ag cermets was studied to be integrated into a packed-bed membrane reactor with potential application in the selective separation of CO2 and O2; and simultaneous syngas production through the coupling of the oxidative CO2 reforming of methane process. The γ-LiAlO2 was chemically synthesized and incorporated into an Ag matrix, in different amounts, by powder metallurgy using ball milling and uniaxial pressing techniques. The obtained cermets exhibit excellent wettability properties against molten carbonates, facilitating their infiltration and forming dense dual-phase membranes with the molten salts. Moreover, the cermet supports show corrosion resistance against the alkaline molten carbonates and superior thermal stability due to the γ-LiAlO2 suppresses the sintering of the metallic phase. The membrane's performance was evaluated in the selective gas separation at high temperatures. The membranes exhibit simultaneous CO2 and O2 permeation with a flux of 0.78 and 0.43 ml·min-1·cm-2, at 850 °C, respectively. Besides, during the oxidative reforming process, the membrane reactor shows conversion of about 100 % of CO2 under the studied separation and reaction conditions. The syngas (H2+CO) production reaches values of 4.94 ml·min-1·cm-2 at 825 °C using a 10 % Ni/CeO2 catalyst. A long-term permeation test was conducted for 225 h, during which the membrane exhibits excellent thermal and chemical stability properties under continuous reaction conditions of syngas production. This fact is attributed to its outstanding chemical inertness against carbonates as well as the observed sinterability properties of the used cermet support. Display omitted •LiAlO2–Ag cermets exhibits remarkable wettability against molten carbonates.•The cermet phase shows chemical resistance to degradation induced by molten carbonates.•Concurrent and stable CO2 and O2 separation are achieved for the long-term test.•Stable behavior of the membrane reactor for the oxidative reforming of methane.