Phase　composition　and　pore　structure　of　La,　Ce,　Y　and　B　doped　unsupported　alumina　membranes　were　investigated　by　means　of　X-ray　diffraction　and　N-2　adsorption.　The　role　of　La,　Ce,　Y　and　B　addition　in　enhancing　the　thermal　stability　of　alumina　membranes　is　discussed.　At　temperatures　ranging　from　800　to　1000　degreesC,　La　and　Y　impregnation　are　more　efficient　than　that　of　B　and　Ce　to　preserve　the　BET　surface　area　and　pore　volume.　The　addition　of　La　can　partially　stabilize　the　alumina　membranes　up　to　1200　degreesC　by　the　delay　of　phase　transformation　from　gamma-　to　alpha-Al2O3.　(C)　2004　Elsevier　B.V.　All　rights　reserved.