The nanoparticles of CoFe2O4, Fe3O4, and ionic liquid-modified Fe3O4 with 1-octyl-3-methylimidazolium bromide, (IL-Fe3O4), have been prepared and their characteristics for adsorption ofalizarin red S dye (ARS) have been compared. The mean size and the surface morphology of the nanoparticles were characterized by TEM, XRD and FTIR techniques. Adsorption of ARS was performed under different experimental conditions in batch technique. The isotherm evaluations show that the Langmuir model obtained better fits with the equilibrium data. The maximum adsorption capacities were 140.8, 192.3 and 256.4 mg of ARS per gram Fe3O4, CoFe2O4 and IL-Fe3O4 nanoparticles, respectively. The applicability of two kinetic models including pseudo-first order and pseudo-second order models were estimated as the basis of comparative analysis of the corresponding rate parameters, equilibrium adsorption capacity and correlation coefficients. The adsorption processes for the case of Fe3O4 and IL-Fe3O4 nanoparticles as adsorbents were endothermic but was exothermic when CoFe2O4 nanoparticles were used. The dye was desorbed by analkaline solution at pH 9.0 from Fe3O4 and by an acidic solution at pH 3.0 from both IL-Fe3O4 and CoFe2O4 nanoparticles. The recovered nanoparticles were successfully reused for more removal of the dye.