Single-walled carbon nanotubes (SWCNTs) were functionalized by chitosan and their application was examined in adsorbing an anti-cancer drug, 5-fluorouracil (5Fu). Surface, physical and morphological characteristics of raw SWCNTs and Chitosan-functionalized SWCNTs (Ch-SWCNTs) were extensively characterized by Fourier transform spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Brunauer-Emmet-Teller (BET) and X-ray diffraction (XRD). The effects of various variables such as pH, initial drug concentration, temperature, and contact time on adsorption capacity were also investigated. Thermodynamic parameters such as ΔSo, ΔHo, and ΔGo were estimated. Isotherm and kinetic studies of drug adsorption indicated that the adsorption process followed Langmuir isotherm model and pseudo-second-order kinetic, respectively. The maximum adsorption capacity (qm) of 5Fu on Ch-SWCNTs was 31.77mg g-1 at 298 K, pH 4.0, and 120 min, which is higher than adsorption capacity of SWCNTs (4.12mg g-1) in the same conditions. The adsorption was spontaneous and exothermic process in nature, with a slight decreasing in entropy.