Plasmas technology is a simple way to functionalize the surface of multi-wall carbon nanotube MWCNT. Homogenous plasma of Ar–N2-H2 gas mixture was generated in radio frequency RF dielectric barrier Discharge DBD at discharge power of 60 W and total pressure of 500 Pa. The active plasma species was monitored by optical emission spectroscopy OES. While the untreated and treated MWCNTs were investigated with various techniques. The result from OES shows complex spectrum with spectral line/bands related various species such as OH, N2, CN, C2, Hα and Are I, confirming the rich plasma environment, as well as possible active interaction between the MWCNTs and the plasma species. The TEM images of the treated samples revealed the roughness of the CNT outer surface. The X-ray photo electron emission XPS results confirm the presence of nitrogen-based functional groups (C–NC, C–NHO and (CO)–N-(CO)) on the plasma treated MWCNTs. Raman spectrum analysis confirms the functionalization of the treated MWCNTs as the ID/IG ratio increased for the treated sample. The Ar–N2-H2 plasma treatment of MWCNTs undamaged the MWCNTs structure and preserved integrity as observed by XRD result and SEM image.