The　aim　of　this　work　is　to　study　the　effect　of　Sr　substitution　on　the　redox　properties　and　catalytic　activity　of　La2-x　Sr　x　NiO　4　(x　=　0.0-1.2)　for　NO　decomposition.　Results　suggest　that　the　x　=　0.6　sample　shows　the　highest　activity.　The　characterization　(TPD,　TPR,　etc.)　of　samples　indicates　that　the　x　=　0.6　sample　possesses　suitable　abilities　in　both　oxidation　and　reduction,　which　facilitates　the　proceeding　of　oxygen　desorption　and　NO　adsorption.　At　temperature　below　700°C,　the　oxygen　desorption　is　difficult,　and　is　the　rate-determining　step　of　NO　decomposition.　With　the　increase　of　reaction　temperature　(T　＞　700°C),　the　oxygen　desorption　is　favorable　and,　the　active　adsorption　of　NO　on　the　active　site　(NO　+　V　o　+　Ni2+　&rarr　NO--Ni3+)　turns　out　to　be　the　rate-determining　step.　The　existence　of　oxygen　vacancy　is　the　prerequisite　condition　for　NO　decomposition,　but　its　quantity　does　not　relate　much　to　the　activity.　©　2007　Science　in　China　Press.