Compared　to　traditional　super　absorbent　polymers　using　raw　materials　from　petrochemical　industry,　natural　polymer　absorbents　are　more　favorable　because　they　are　sustainable　and　biodegradable.　In　this　study,　composite　absorbents　were　developed　by　crosslinking　carrageenan　with　sodium　alginate　using　calcium　chloride.　Effect　of　composition　on　absorption　was　tested.　Absorption　was　improved　by　increasing　carrageenan　content.　The　super　absorbent　exhibited　the　maximal　swelling　ratio　of　13.1　g/g　in　0.9%　saline　water　in　just　5　min.　The　maximal　tensile　strength　was　reached　with　a　value　of　12.8　MPa.　Water　contact　angle　revealed　that　carrageenan　is　more　hydrophobic　than　sodium　alginate.　Presence　of　sulfate　groups　might　be　a　key　factor　promoting　absorption.　The　scanning　electron　microscopic　images　showed　that　the　composite　material　had　a　structure　with　alginate　arranged　at　the　outside　surface.　These　results　demonstrate　that　a　sustainable　and　biodegradable　absorbent　was　successfully　developed　with　a　matrix　of　properties　for　potential　application　in　diapers.　©　2016　Elsevier　B.V.