The　electronic　structures　and　the　hydrogenation　of　a　chiral　single-wall　(6,4)　carbon　nanotube　have　been　investigated　by　density　functional　theory.　Our　results　indicate　that,　along　the　long　vector　of　the　tube,　the　HOMO　and　LUMO　exhibit　well-regulated　arrangement　of　the　bonding　and　anti-bonding　structures.　The　adsorption　of　odd　hydrogen　atoms　on　the　tube　leads　to　obvious　deformations　of　the　tubular　structure　and　the　hydrogenation　of　the　(6,4)　tube　can　be　well　predicted　by　examining　the　topology　of　HOMO.　(c)　2005　Elsevier　B.V.　All　rights　reserved.