Cu-Al-O　thin　films　were　prepared　by　rf　magnetron　sputtering.　By　adjusting　oxygen　partial　pressure,　the　effect　of　oxygen　on　optical　transmission　and　electrical　properties　of　the　films　were　investigated.　The　films　exhibit　good　transparency　in　the　visible　range.　As　oxygen　partial　pressure　is　above　30%,　the　transmittance　is　about　60-70%.　The　direct　and　indirect　band　gaps　are　about　3.49　and　1.86　eV,　respectively.　The　linear　I-V　relations　exhibit　ohmic　contacts　between　Ag　and　the　films,　which　suggest　that　the　work　function　of　Cu-Al-O　thin　films　is　around　4.26　eV.　In　the　temperature　range　of　250-3　10　K,　the　temperature　dependence　of　the　conductivity　of　Cu-Al-O　thin　films　is　of　semiconducting　thermal-activation　type.　The　average　conductivity　at　room　temperature　successively　increases　as　the　oxygen　partial　pressure　augments.　The　maximurn　conductivity　is　4.6　x　10(-3)　S　cm(-1)　for　Cu-Al-O　thin　film　deposited　at　40%　oxygen　partial　pressure.　When　above　40%,　the　decrease　of　the　conductivity　may　be　due　to　the　inhibition　of　the　carrier　transport　led　by　the　semiconductor　trap　states　originated　from　the　excess　oxygen　atoms.　(c)　2007　Elsevier　B.V.　All　rights　reserved.