In　this　paper,　biosorption　of　C.I　Acid　Yellow　199　on　magnetic　sargasso　from　wastewater　was　studied.　The　influence　of　initial　pH,　temperature,　initial　dye　concentration　and　biosorbent　dose　were　investigated　by　a　series　of　static　adsorption　experiments.　It　was　observed　that　the　optimum　initial　pH　value　was　2.0.　The　Langmuir　and　Freundlich　isotherm　models　were　applied　to　describe　the　biosorption　isotherm.　It　found　that　Langmuir　model　fitted　the　equilibrium　data　better.　The　calculated　thermodynamic　parameters,　such　as　G,　H　and　S　showed　that　the　biosorption　was　spontaneous　and　exothermic　under　examined　conditions.　©　2011　IEEE.