In　order　to　understand　the　biosorption　of　Basic　Organic　(BO)　textile　dye　on　dried　Azolla　filiculoides　(A.　filiculoides),　batch　experiments　were　conducted　under　various　conditions.　The　results　show　that　biosorption　of　BO　on　dried　A.　filiculoides　was　dependent　on　the　initial　solution　pH,　biosorbent　dosage,　contact　time　and　the　initial　BO　concentration.　Using　the　Langmuir　equation,　the　biosorption　capacity　(qm)　for　BO　was　833mg/g　at　303K.　The　kinetic　study　suggested　that　the　mechanism　of　biosorption　was　due　to　ion-exchange　physisorption　via　the　intra-particle　diffusion　and　chemisorption　on　the　external　surface　of　dried　A.　filiculoides.　Different　techniques　were　used　to　characterize　dried　A.　filiculoides　and　indicated　that　the　biomass　had　a　high　cation　exchange　capacity　(93.6mmol/100g),　a　large　specific　surface　area　(80.35-422.89m2/g)　and　contained　various　functional　groups　which　may　play　an　important　role　in　the　physisorption　and　chemisorption　of　BO　on　the　surface　of　A.　filiculoides.　The　results　showed　that　the　removal　ratio　of　BO　reached　79.3%　from　wastewater　containing　100mg/L　BO,　indicating　that　the　biomass　could　be　used　as　a　potential　biosorbent　for　the　removal　of　BO　from　industrial　wastewater.　©　2010　Elsevier　B.V.