A process for the in-situ formation of a lubricating phase comprising sulphur and tin in a friction material, wherein reaction of a sulphur source with a tin source in said friction material results in the formation of said lubricating phase, and wherein said reaction is initiated or effected by heat resulting, in use, from the generation of friction, wherein said sulphur source is selected from one or both of sulphur and/or a metal sulphide selected from one or more of iron, copper, zinc, titanium and bismuth, and wherein said tin source is selected from one or more of tin, a tin-containing compound and/or a tin-containing alloy.