A vacuum pump may include a rotor and a stator, wherein the rotor is supported by metal bearings (such as steel bearings) to allow relative rotation of the rotor with respect to the stator. A liquid PFPE lubricant compound is provided to lubricate the bearings, wherein the lubricant further comprises a solid lubricant that is in suspension in the liquid lubricant. The solid lubricant can comprise any of graphite, graphene and molybdenum disulphide. In other words, the inventive concept encompasses a lubricated bearing arranged to support a rotating shaft in a body under sub-atmospheric conditions, wherein a lubricant used to lubricate the bearing comprises liquid PFPE lubricant having a low vapour pressure, and a solid lubricant that is held in suspension in the liquid lubricant. The solid lubricant may comprise any of graphite, graphene and molybdenum disulphide.