Thin transfer films were formed on steel surfaces during friction against graphite-based pins. Sodium thiosulfate Na2S2O3 or sodium molybdate Na2MoO4 were added to graphite to improve the film formation. In order to understand the solid lubricant properties of the graphite + additive mixtures, physico-chemical characterization was performed using classical theta-2 theta and grazing-incidence X-ray diffraction, thermogravimetry, Raman and micro-Raman spectroscopy and transmission electron microscopy. The graphite + additive pins before and after friction tests and the transfer films were analysed.