Multi-walled　carbon　nanotubes　(MWCNTs)　were　synthesized　by　hydrogen　DC　arc　discharge　at　elevated　environment　temperature.　The　sample　collected　from　the　soot　on　the　inner　wall　of　the　are　discharge　furnace　was　investigated　using　TEM,　HRTEM　and　X-ray　diffraction.　The　results　show　that　environment　temperature　has　a　significant　effect　on　the　formation　of　MWCNTs　in　the　soot　in　hydrogen　atmosphere　as　well　as　the　diameter　of　the　tubes.　When　environment　temperature　in　the　furnace　is　higher　than　about　500　degrees　C,　MWCNTs　can　be　formed　on　the　furnace　walls　with　a　great　quantity.　(c)　2006　Elsevier　B.V.　All　rights　reserved.