Abstract: Multi-walled and single-walled carbon nanotubes were used as adsorbents for the removal of Reactive Blue 19 textile dye from aqueous solutions. The adsorbents were characterised by scanning and transmission electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were investigated. The maximum adsorption of dye was observed in the acidic pH region using both adsorbents. The contact time to obtain equilibrium isotherms at 298-323 K was fixed at 2 h for both adsorbents. The equilibrium data were analyzed using three widely applied isotherms: Langmuir, Freundlich and Liu isotherm models. The results revealed that Liu isotherm fit the experimental results well. The maximum sorption capacity for adsorption of the dye occurred at 323 K, attaining values of 450 and 550 mg g^-1 for MWCNT and SWCNT, respectively. Standard free energy (ΔG°), standard enthalpy (ΔH°) and standard entropy (ΔS°) were calculated by the data obtained from Liu equation at different temperatures. All ΔG° were negative. The Δh° and ΔS° values were positive; indicating that the reactive blue adsorption was spontaneous and endothermic process.