Biosorption　using　agricultural　wastes　has　been　proven　as　a　low　cost　and　efficient　way　for　wastewater　treatment.　Herein,　grape　peel　treated　by　microwave-　and　conventional-hydrothermal　processes　was　used　as　low　cost　biosorbent　to　remove　methylene　blue　(MB)　from　aqueous　solutions.　The　adsorption　parameters　including　the　initial　pH　value,　dosage　of　biosorbents,　contact　time,　and　initial　MB　concentration　were　investigated　to　find　the　optimum　adsorption　conditions.　The　biosorbent　obtained　by　microwave-hydrothermal　treatment　only　for　3　min　at　180　°C　(microwave-hydrothermal　treated　grape　peel,　MGP)　showed　faster　kinetics　and　higher　adsorption　capability　than　that　produced　by　a　conventional-hydrothermal　process　(hydrothermal　treated　grape　peel,　HGP)　with　a　duration　time　of　16　h.　The　maximum　adsorption　capability　of　MGP　under　the　optimum　conditions　(pH　=　11,　a　dosage　of　2.50　g/L)　as　determined　with　the　Langmuir　model　reached　215.7　mg/g,　which　was　among　the　best　values　achieved　so　far　on　biosorbents.　These　results　demonstrated　that　the　grape　peel　treated　by　a　quick　microwave-hydrothermal　process　can　be　a　very　promising　low　cost　and　efficient　biosorbent　for　organic　dye　removal　from　aqueous　solutions.　©　2018　by　the　authors.　Licensee　MDPI,　Basel,　Switzerland.