AbstractThe present contribution reports on inorganic oxygen transport membranes (OTM) investigated in a specific task of the BIGCO2 project, which is one amongst the largest CCS projects in Scandinavia. The membranes are used for separation of oxygen from air at temperature typically above 800 °C. The work reports on selected membrane materials La2−xNiO4+δ belonging to the Ruddlesden-Popper phase family. While La2NiO4+δ membranes are well-known candidates for OTM application, two new materials with molar ratio La/Ni<2 are presented in this publication and their transport properties for the first time reported. Furthermore, selected results on membrane fabrication, sealing technology and assembly of small modules are presented to demonstrate the progress of the work.