The　electrochemiluminescence　(ECL)　behavior　of　luminol　on　a　nafionnano-TiO2　modified　glassy　carbon　electrode　(nafionnano-TiO2?GCE)　was　studied.　Two　ECL　peaks　(ECL-1　and　ECL-2)　were　found　during　cathodic　potential　scanning.　ECL-1　at　ca-0.4　V　(vs　Ag-AgCl　reference　electrode)　came　from　the　reaction　between　luminol　and　active　oxygen　anion　produced　at　the　GCE　surface　directly,　while　ECL-2　at　ca-0.9　V　(vs　Ag-AgCl　reference　electrode)　came　from　the　reaction　between　luminol　and　the　active　oxygen　anion　catalyzed　by　TiO2.　The　possible　mechanism　for　the　generation　of　both　ECL　peaks　has　been　proposed.　The　reproducibility　of　the　ECL　intensities　on　nafionnano-TiO2-GCE　at　ECL-1　and　ECL-2　was　good,　with　relative　standard　deviations　(n　=　10)　of　4.3　and　1.3%,　respectively.　The　ECL-2　generated　at　the　nafionnano-TiO2-GCE　surface　was　further　developed　to　detect　the　dissolved　oxygen,　and　a　detection　limit　of　0.02　mg/L　was　achieved.　The　proposed　method　was　applied　to　detect　dissolved　oxygen　in　water　with　satisfactory　result.　Copyright　(C)　2010　John　Wiley　&　Sons,　Ltd.