A　new　sensor　based　on　the　porous　plastic　probe　has　been　developed　for　the　detection　of　dissolved　oxygen.　This　probe　was　prepared　by　co-polymerization　of　monomer,　cross-linking　reagent,　porogent　and　luminescent　ruthenium(II)diimine　complex.　The　porous　plastic　probe　exhibits　good　response　to　dissolved　oxygen　and　resistance　to　indicator　leaching　out　due　to　its　high　hydrophobicity.　The　preparation　and　characteristics　of　the　probe　were　investigated　in　detail.　This　porous　plastic　probe　serves　as　anal　yte-sensitive　function　as　well　as　optical　wave-guide,　which　make　it　easy　to　assemble　the　fiber-optical　chemical　sensor　(FOCS).　The　developed　sensor　has　been　applied　to　the　determination　of　dissolved　oxygen　in　seawater　with　satisfactory　results　compared　with　the　standard　method.　(c)　2007　Elsevier　B.V.　All　rights　reserved.