Modification of carbonaceous materials

A modified carbonaceous material having chemically bound on its surface at least one fluoropolyoxyalkylene chain (chain R.sub.f) and a process for the modification of a carbonaceous material [material (C)]. The process comprises: contacting the material (C) with a (per)fluoropolyether peroxide comprising at least one peroxidic moiety comprised between sp.sup.3 carbon atoms and at least one fluoropolyoxyalkene chain (chain R.sub.f), i.e. a fluorocarbon segment comprising ether linkages in main chain [peroxide (P)]; and heating the material (C) while in contact with the peroxide (P) at a temperature exceeding decomposition temperature of the peroxide (P).