Molybdenum disulfide is an inorganic compound with the chemical formula MoS2, it is a silvery black compound most commonly milled to a fine powder. It occurs naturally as the mineral molybdenite, which is the the principal ore for molybdenum.

Due to its layered structure, MoS2 has a low coefficient of friction which makes it an extremely effective solid lubricant or as an additive within greases. When the lubricating oil film degrades over time or due to the application of extreme pressure the Molybdenum Disulfide within the grease provides additional protection for the metal surface. MoS2 is typically far more robust than other compounds with layered structures such as graphite.