Multi-walled carbon nanotubes(MWCNTs) were grafted with poly(N-vinyl-2-pyrrolidone) and with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) at different compositions by using γ-rays technique as initiator. The MWCNTs, MWCNT-graft-PNVP, MWCNT-graft-PAMPS and MWCNTs-graft-P(NVP-co-AMPS) were characterized by Fourier transform infra red(FTIR) spectroscopy, X-ray diffraction(XRD), thermal gravimetric analysis(TGA), elemental analysis and high-resolution transmission electron microscopy(HR-TEM). The results indicated that the grafting processes of PNVP, PAMPS and P(NVP-co-AMPS) occurred on to the surfaces of MWCNTs without destroying the framework of MWCNTs. Tramadol hydrochloride(TH) was loaded as model drug and its release behavior was analyzed via various kinetic models. Release of the loaded TH was studied in simulated gastric fluid(SGF, p H = 1.2) and simulated intestinal fluid(SIF, p H = 7.4) at 37 °C. Controlled release of TH from grafted MWCNTs was investigated. The outcome results suggest that the grafted MWCNTs could be used as a promising matrix candidate for oral drug delivery system by harmonization between the composition and p H level of the simulated biological fluids. Multi-walled carbon nanotubes (MWCNTs) were grafted with poly (N-vinyl-2-pyrrolidone) and with poly (2-acrylamido-2-methyl- 1 -propanesulfonic acid) at different compositions by using γ-ray technique as initiator. MWCNTs-graft-PAMPS and MWCNTs-graft-P (NVP-co-AMPS) were characterized by Fourier transform infra red (FTIR) spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), elemental analysis and high-resolution transmission electron microscopy (HR-TEM). The results indicated that the grafting processes of PNVP, PAMPS and P (NVP-co-AMPS) occurred on to the surfaces of MWCNTs without destroying the framework of MWCNTs. Tramadol hydrochloride (TH) was loaded as model drug and its release behavior was analyzed via various kinetic models. Release of the loaded TH was studied in simulated gastric fluid (SGF, p H = 1.2) and simulated intestinal fluid p H = 7.4) at 37 ° C. Controlled release of TH from grafted MWCNTs was investigated. The outcome re sults suggest that the grafted MWCNTs could be used as a promising matrix candidate for oral drug delivery system by harmonization between the composition and p H level of the simulated biological fluids.