A　electrochemiluminescent　(ECL)　sensor　has　been　designed　to　detect　hexavalent　chromium　(Cr(VI))　in　environmental　water　samples　based　on　the　fact　that　Cr(VI)　can　collisionally　quench　the　ECL　signal　of　graphene　quantum　dots/peroxodisulfate　(GQD/S2O82-)　system.　After　optimizing　some　important　experimental　conditions　including　the　concentrations　of　GQDs　and　S2O82-,　response　time,　and　pH　value　of　solution,　the　ECL　sensor　has　been　finally　developed.　The　ECL　sensor　exhibits　a　wide　linear　response　range　(50　nM-60　mu　M),　excellent　selectivity,　and　high　sensitivity　(detection　limit　of　20　nM,　S/N　=　3).　Furthermore,　the　developed　sensor　has　been　applied　in　the　detection　of　Cr(VI)　in　a　spiked　river　water.　The　result　suggests　that　the　sensor　can　offer　a　simple,　green,　low　cost,　high　selectivity　and　sensitivity　detection　of　Cr(VI).　(C)　2014　Elsevier　Ltd.　All　rights　reserved.