Abstract: Dispersibility and stability of chemical functionalized multi-walled carbon nanotubes (f MWCNTs) in aqueous solution by using small amount of a cationic ionic liquid (IL), 1- tetradecyl-3-methylimidazolium Chloride, [C14mim]Cl, was investigated and was compared with unfunctionalized MWNTs. The surface modification of MWCNTs was done by acid treatment. The f-MWCNTs are extensively characterized by using FT-IR spectroscopy. Using UV-vis spectroscopy was proved that the presence of functional group on the side wall of MWCNTs significantly affected their dispersibility in an aqueous solution which contains a small amount of imidazolium based IL as dispersing agent.