This article contains microstructural characterization data related to the research article ‘Self-lubrication of Nuclear Graphite in Argon at High Temperature’, published in Tribology International. Digital, optical, and scanning electron micrographs are collected on the pebble and disk samples generated in the tribological tests and in their corresponding reference samples. Surface roughness measurements of the test and control samples are performed using the 3D-depth composition feature of the digital microscope. X-ray diffraction and Raman spectra of the test and reference samples are acquired and peak-fitted according to published literature on nuclear graphite characterization. Plots of the peak-fitted spectra are included in this article; the full list of peak-fitting parameters is provided in the linked data repository.