A　series　of　supported　Ni　catalysts　have　been　prepared　from　NixMg3-xAl　hydrotalcite-like　compounds　(HTlcs)　and　the　influence　of　Ni:Mg　molar　ratio　on　the　structural　property　and　catalytic　activity　for　CO2　methanation　is　investigated.　The　catalysts　were　characterized　by　N-2　physical　adsorption,　X-ray　powder　diffraction　(XRD),　temperature-programmed　reduction　(H-2-TPR),　temperature-programmed　desorption　(CO2-TPD),　H-2　chemisorption,　scanning　electronic　microscopy　(SEM),　scanning　transmission　electronic　microscopy　(STEM),　and　diffuse　reflectance　infrared　Fourier　transform　spectroscopy　(DRIFTS).　By　reducing　HTlcs　at　800　degrees　C,　well　dispersed　Ni　particles　with　average　size　of　5-10　nm　are　formed.　The　Ni　crystal　size　decreases　with　the　decrease　of　Ni:Mg　ratio,　attributable　to　the　strong　interaction　between　nickel　and　magnesium　oxides.　Among　the　catalysts,　Ni2Mg1Al-HT　shows　the　highest　activity,　giving　similar　to　93%　CO2　conversion　and　＞99%　CH4　selectivity　at　275　degrees　C　and　SV　=　5000　mL　g(-1)　h(-1).　Meanwhile,　this　catalyst　exhibits　good　stability　without　obvious　sintering　and　coking.　The　high　activity　is　related　to　the　large　amount　of　surface　Ni-0　species　and　medium　basic　sites.　From　CO2-TPD　and　DRIFTS,　it　is　inferred　that　CO2　adsorbs　on　the　medium　basic　sites,　i.e.,　NieMg(Al)O　interface,　forming　monodentate　carbonate.　In　situ　DRIFTS　reveals　that　monodentate　carbonate,　monodentate　formate,　and　adsorbed　CO　are　the　main　intermediate　species,　suggesting　that　the　reaction　may　proceed　via　the　formate　formation　route.　(C)　2022　Hydrogen　Energy　Publications　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.