A chemical treatment was applied to functionalize multiwalled carbon nanotubes (MWCNTs) to introduce -COOHand -OH groups on the surface for better interfacial interaction with an epoxy matrix. The functionalized MWCNT (f-MWCNT) reinforced epoxy nanocomposites were prepared with varying compositions up to 1 wt% MWCNTs. The interaction between MWCNTs and epoxy matrix was evidenced by Fourier transform infrared spectroscopy. The structure and microstructure of f-MWCNTs reinforced epoxy composite were studied by X-ray diffraction, field emission scanning electron microscope, high-resolution transmission electron microscope, and Raman spectroscope. The orientation of f-MWCNT was investigated by an atomic force microscope. The incorporation of f-MWCNTs enhanced the thermal stability and the conductivity of the epoxy matrix significantly. The results of tensile strength, tensile strain, extension, and load at break clearly revealed a substantial improvement in tensile properties of the epoxy matrix due to homogeneous dispersion of f-MWCNTs in the epoxy matrix and strong interfacial adhesion between them as well. The improvement in thermal and mechanical properties in combination with an increase in electrical properties may make the material suitable for making electronic devices. C 2016 Wiley Periodicals, Inc. Adv Polym Technol 2016, 0, 21654; View this article online at wileyonlinelibrary.com.