Chitosan　nanoparticles　(chitosan　NP)　were　effectively　incorporated　onto　cotton　fiber　surfaces　during　a　green　adsorption　without　any　cross-linking　agents　in　this　work.　The　interactions　between　cotton　fibers　and　chitosan　NP　during　the　green　adsorption　were　investigated　by　Fourier　transform　infrared　spectroscopy　(FTIR),　X-ray　photoelectron　spectroscopy　(XPS),　X-ray　diffraction　(XRD),　thermogravimetric-derivative　thermogravimetry　(TG-DTG)　and　scanning　electron　microscopy　(SEM)　in　detail.　The　results　indicated　that　the　intermolecular　hydrogen　bond　interactions　exited　between　the　hydroxyl　groups　of　cotton　fibers　and　the　amino　groups　of　chitosan　NP,　and　progressively　enhanced　with　the　increase　in　chitosan　NP　mass　concentrations.　After　chitosan　NP　adsorption,　the　acidity　of　fibers　augmented　and　the　crystallinity　index　of　fibers　declined　owing　to　the　increasing　interactions.　In　addition,　the　hydrophobic　interactions　occurred　between　chitosan　NP　and　crystalline　cotton　fibers,　thereby　resulting　in　the　preferential　adsorption　onto　the　hydrophobic　(2　0　0)　crystallographic　plane.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.