Abstract: Plasma electrolytic oxidation (PEO) in Na₂SiO₃-KOH electrolytes with different solid lubricant additives are used to produce solid lubricant-containing PEO coatings on LY12 aluminum alloy. The composition and microstructure of the PEO coating, PTFE-containing PEO coating and graphite/PTFE co-containing PEO coating are analyzed by using fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). The tribological properties of PEO coatings are evaluated on a reciprocating ball-on-disk tribometer. The results show that the solid lubricant additives incorporated successfully into the PEO coatings. PTFE-containing PEO coatings exhibit lower friction coefficient than that of the PEO coatings. The graphite/PTFE-PEO coating has the lowest friction coefficient.