Abstract: To deepen the understanding of molecular interaction between Ionic liquids and carbon nanotube, as well as to investigate the influence of the ionic liquids tail length on the adsorption process, we report here the first detailed the adsorption and morphology of aggregates of the ionic liquids containing imidazolium ionic liquids ([Cnmim] Cl, n=10,12,14,16) on multi-walled carbon nanotube (MWCNT) surfaces. We make a comparison between the various ILs adsorptions onto MWCNT to clarify the role of the ionic liquid tail length on the adsorption process. This comparison indicates that by increasing the tail length the larger number of the ionic liquid molecules tend to adsorb onto MWCNT which can be attributed to the fact that the [Cnmim] Cl with n=16 has a longer chain. In addition, our results show that a longer chain yields the higher packed aggregates in which the IL heads are extended far into the aqueous phase, which in turn may increase the MWCNTs stabilization in aqueous suspensions.