A　hydrophobic　thiol-functionalized　ionic　liquid　(IL)　was　synthesized　and　immobilized　tightly　on　a　gold　electrode　surface　via　Au-S　bond　to　construct　a　stable　Au-IL　vertical　bar　water　interface.　At　the　Au-IL　vertical　bar　water　interface,　the　electrochemiluminescence　(ECL)　of　luminol-O-2　system　was　investigated.　The　ECL　intensity　of　luminol-O-2　system　at　the　Au-IL　vertical　bar　water　interface　was　much　larger　and　more　stable　than　that　at　Au　vertical　bar　water　interface.　The　enhanced　ECL　mechanism　at　the　Au-IL　vertical　bar　water　interface　was　studied　and　discussed　in　details.　(C)　2009　Elsevier　B.V.　All　rights　reserved.