A facile strategy for the preparation of organic nitrogen functional multi-walled carbon nanotubes (MWCNTs) in aqueous solution is proposed, where MWCNTs were functionalized by simultaneous radiation-induced graft polymerization of acrylamide under the γ-ray. The structure of the poly(acryl amide) grafted MWCNTs (denoted as MWCNT-g-PAM) is characterized by means of FT-IR, XPS spectroscopies, TGA analysis and TEM imaging. The degree of grafting dependent on the reaction conditions such as the monomer concentration was also discussed in this paper. © 2018 Taylor & Francis Group, LLC.