Abstract: Graphite or carbon particles with a graphitic skin are intercalated with a compound including an oxidized form of a metal and then reduced in a hydrogen atmosphere. This process reduces the driving force for the galvanic reaction between the particles and active metals in aqueous environments. The particles may be present as a reinforcement for a metal matrix (e.g., graphite/aluminum metal matrix composites) or as a reinforcement for a non-metallic material (e.g., graphite/polyimide, graphite/polyester or graphite/cyanate composites). In the latter case, the composite is adjacent to a metal in a structure.By way of example, the graphite or carbon particle may be a fiber, the metal subject to attack may be aluminum or magnesium, and the intercalation compound may be NiCl.sub.2.