La1-xSrxMnO3-delta　(x=0.4,　0.5,　and　0.6)　catalysts　were　fabricated　hydrothermally　from　KMnO4,　MnCl2　(KMnO4/MnCl2　molar　ratio　=　3/7),　and　stoichiometric　amounts　of　lanthanum　and　strontium　nitrates　in　KOH　solution.　The　physicochemical　properties　of　the　materials　were　characterized　by　a　number　of　analytical　techniques.　It　was　found　that　the　La1-xSrxMnO3-delta　samples　fabricated　at　250　degrees　C　are　single-crystalline　perovskite-type　oxides　in　the　form　of　microcubes.　The　as-fabricated　La1-xSrxMnO3-delta　materials　display　various　states　of　oxygen　nonstoichiometry.　The　total　amount　of　oxygen　vacancies　and　Mn4+　in　the　catalysts　decreases　in　the　order　of　La0.5Sr0.5MnO3-delta　＞　La0.4Sr0.6MnO3-delta　＞　La0.6Sr0.4MnO3-delta.　It　has　been　found　that　the　trends　of　catalyst　reducibility　and　catalytic　performance　of　the　three　catalysts　follow　a　similar　order.　We　observed　100%　toluene　conversion　at　255　degrees　C　over　the　La0.5Sr0.5MnO3-delta,S　Catalyst,　113　degrees　C　lower　than　that　observed　over　a　polycrystalline　La0.5Sr0.5MnO3-delta　catalyst　prepared　by　calcination　at　950　degrees　C.　The　excellent　performance　of　the　former　c,in　be　related　to　the　high　Mn4+/Mn3+　ratio,　distinct　oxygen　nonstoichiometry,　and　single-crystalline　structure　of　the　catalyst.　(C)　2008　Elsevier　B.V.　All　rights　reserved.