Abstract The carbon derived from the thermal treatment of modified phenolic resins (PR) tends to organize into graphitic lamellae or turbostratic carbon and is commonly considered non-graphitizable. In this study, nanocomposites were synthesized with modified phenolic resin (Novolac) used as the matrix and oxidized multi-walled carbon nanotubes (NTox) in amounts ranging from 0.3 to 2.5 wt% as a filler. Thermal gravimetric analysis (TGA), Raman spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) with field emission gun (FEG), and transmission electron microscopy (TEM) were performed. By TGA, the PR-2.5 wt% nanocomposite showed less thermal degradation and higher stability when compared to the pure matrix after heat treatment up to 1000 °C. Graphitic carbon organization analysis by Raman spectroscopy, XRD, SEM/FEG, and TEM micrographs showed that the PR-2.5 wt% nanocomposite is suitable for technological applications, involving a carbon graphitization tendency.