TiO2　nanocrystals　had　been　modified　on　the　surface　of　the　glassy　carbon　electrode　(GCE)　with　the　help　of　Nafion.　The　electrochemiluminescence　(ECL)　behavior　of　the　TiO2/Nafion　GCE　in　aqueous　solution　was　investigated.　A　possible　mechanism　about　the　ECL　of　TiO2　had　also　been　proposed.　The　ECL　intensity　was　linear　with　the　dissolved　oxygen　concentration　in　the　range　of　0.30-10.00　mg/L　with　a　detection　limit　of　0.12　mg/L.　The　developed　method　can　be　applied　to　detect　the　dissolved　oxygen　concentration　or　biochemical　oxygen　demand　(BOD).　(C)　2008　Elsevier　B.V.　All　rights　reserved.