In　recent　years,　considerable　efforts　have　been　devoted　to　the　construction　of　efficient　enzyme　mimetics,　which　have　significant　advantages　of　simple　synthesis,　good　stability　and　design　flexibility.　In　this　paper,　we　described　that　graphene　dots　(GDs)　possess　highly-efficient　peroxidase-like　catalytic　activity,　and　its　activity　is　much　higher　than　graphene　oxide　(GO)　with　large　size.　They　can　catalyze　the　oxidation　of　peroxidase　substrate　3,3,5,5-tetramethylbenzidine　(TMB)　in　the　presence　of　H2O2　to　produce　a　blue　product,　which　can　be　used　for　H2O2　detection　by　measuring　the　absorbance　change.　This　catalytic　reaction　can　be　also　used　for　other　analyte　detection　by　monitoring　the　generation　or　consumption　of　H2O2,　such　as　glucose　and　reduced　glutathione　(GSH).　The　GDs-based　system　permits　detection　of　as　low　as　10　nM　H2O2,　which　is　much　lower　than　that　of　other　nanomaterials-catalyzed　methods.　Meanwhile,　the　detection　limit　of　this　system　is　0.5　mu　M　for　glucose　and　0.5　mu　M　for　GSH,　respectively.　Furthermore,　the　proposed　system　also　shows　high　selectivity　and　is　capable　of　sensing　in　complicated　biological　samples　such　as　cell　lysate.　Due　to　their　high　catalytic　activity,　high　diffusion　and　excellent　biocompatibility,　GDs　can　be　expected　to　be　applied　in　various　fields,　such　as　biotechnology,　medical　diagnostics　and　environmental　monitoring.　(c)　2013　Elsevier　B.V.　All　rights　reserved.