Dry lubricants or solid lubricants are materials which despite being in the solid phase, are able to reduce friction between two surfaces sliding against each other without the need for a liquid media. Such lubricants, including materials such as graphite, hexagonal boron nitride, molybdenum disulfide and tungsten disulfide are also able to offer lubrication at temperatures higher than liquid and oil-based lubricants are able to operate. Such materials can operate up to 350°C in oxidising environments and even higher in reducing / non-oxidising environments (molybdenum disulfide up to 1100°C). Their lubricating properties are attributed to a layered structure on the molecular level with weak bonding between layers. Such layers are able to slide relative to each other with minimal applied force, thus giving them their low friction properties.

Limited interest has been shown in low friction properties of compacted oxide glaze layers formed at several hundred degrees Celsius in metallic sliding systems, however, practical use is still many years away due to their physically unstable nature.

The three most commonly used solid lubricants are

• Graphite - Used in air compressors, foodstuff industry, railway track joints, open gear, machine-shop works etc.
• Molybdenum disulfide - Used in space vehicles.
• Hexagonal boron nitride - Used in space vehicles. Also called "white graphite".

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