La-Co-O　mixed　oxides　(LCO)　were　prepared　by　co-precipitation　method　with　the　presence　of　polyethylene　glycol　(PEG)　as　dispersant.　The　influence　of　adding　different　molecular　weight　of　PEG　(0,　2　000,　6　000,　20　000　g·mol-1)　on　the　physicochemical　and　catalytic　properties　of　La-Co-O　mixed　oxides　for　total　oxidation　of　benzene　was　investigated.　The　samples　were　characterized　by　means　of　N2　physical　adsorption,　X-ray　diffraction　(XRD),　scanning　electron　microscopy　(SEM),　temperature-programmed　reduction　by　H2　(H2-TPR),　temperature-programmed　desorption　of　O2　(O2-TPD),　and　X-ray　photoelectron　spectroscopy　(XPS).　The　order　of　catalytic　activity　was　found　to　be　LCO-PEG6000＞LCO＞LCO-PG20000＞LCO-PG2000.　Particularly,　LCO-PEG6000　exhibited　benzene　conversion　of　99%　at　temperature　as　low　as　383,　which　was　126　lower　than　that　of　LCO.　The　characterization　result　reveals　that　all　samples　had　a　BET　surface　area　of　about　9~10　m2·g-1.　The　XRD　result　shows　that　on　all　samples　LaCoO3　perovskite　was　mainly　formed　together　with　a　small　amount　of　La2O3　and　Co3O4.　The　addition　of　PEG　was　favorable　for　the　formation　of　LaCoO3　perovskite.　Particularly,　the　addition　of　PEG-6000　effectively　suppressed　the　agglomeration　of　LaCoO3　perovskite,　giving　rise　to　small　and　uniform　particles　as　observed　by　SEM.　Moreover,　the　results　of　H2-TPR　and　O2-TPD　indicate　that　the　obtained　La-Co-O　mixed　oxides　showed　higher　reducibility　and　lattice　oxygen　mobility,　and　the　Co　2p　XPS　analysis　suggests　that　more　surface　Co3+　active　species　were　presented　by　the　addition　of　PEG-6000.　These　properties　are　thought　to　contribute　to　the　high　activity　in　benzene　total　oxidation.　©　2016,　Peking　University　Press.　All　right　reserved.