Attempts have been made to fabricate a bicomponent composite reinforcing element comprised of a central core of carbon fibre filaments surrounded by a cylindrical silicon carbide sheath. Such fibres are particularly attractive for composite reinforcement since they are potentially capable of exhibiting “duplex” type behaviour, thereby providing a possible means of minimizing anisotropy effects and increasing composite fracture toughness and ductility. Furthermore these elements should provide additional advantages such as eventually enabling multi-filament tows of high strength, low modulus carbon fibre to be formed into large compound fibres which combine high specific strength with a significantly improved overall Young's modulus arising from the stiffness of the ceramic sheath, which should also exhibit a high resistance to chemical attack. Methods of consolidating the multi-filament tow prior to coating have been investigated and suitable preliminary treatments evolved; tows have been coated with silicon carbide using a conventional vapour phase deposition technique to form elements basically conforming to “duplex” requirements. Initial tensile tests upon these elements are reasonably encouraging and reveal none of the side effects encountered previously with boron coatings; it is anticpated that much stronger silicon carbide tubes may be fabricated eventually by this technique using more closely controlled reaction conditions.