In　this　work,　a　Ni-supported　CeO2-Al2O3　catalyst,　called　NiCeAl-RMO　(reduced　metal-oxide),　was　prepared　via　air　calcination　and　H-2　reduction　of　NiCeAl-LDH　(layered　double　hydroxide).　The　NiCeAl-RMO　catalyst　shows　superior　CO2　methanation　activity,　especially　at　low　temperature　(250　degrees　C),　and　it　performed　78.6%　CO2　conversion　with　similar　to　100%　CH4　selectivity.　Compared　with　NiAl-RMO,　the　NiCeAl-RMO　catalyst　prepared　via　the　Ce-doping　strategy　has　significantly　improved　CO2　methanation　activity.　Characterizations　revealed　that　Ce　doping　would　increase　the　amount　of　active　Ni-0　species,　cause　a　large　number　of　oxygen　vacancies,　and　generate　new　moderate　basicity　sites　on　the　catalyst.　In　addition,　in　situ　DRIFTS　found　that,　unlike　the　RWGS　+　CO　methanation　mechanism　over　NiAl-RMO,　the　CO2　methanation　mechanism　over　NiCeAl-RMO　followed　the　formate　pathway　by　generating　bidentate　carbonate　species,　which　was　revealed　as　a　key　intermediate　for　enhancing　the　low-temperature　activity　of　CO2　methanation.