Composite reinforcer (R-2) capable of adhering directly to a diene rubber matrix, which can be used as a reinforcing element for a pneumatic tyre, comprising: one or more reinforcing thread(s) (20), for example a carbon steel cord; covering said thread, individually each thread or collectively several threads, a layer of a thermoplastic polymer composition comprising at least one thermoplastic polymer, the glass transition temperature of which is positive, a poly(p-phenylene ether) (PPE) and a functionalized unsaturated thermoplastic styrene (TPS) elastomer, the glass transition temperature of which is negative, said TPS elastomer bearing functional groups selected from epoxide, carboxyl and acid anhydride or ester groups. Process for manufacturing such a composite reinforcer and rubber article or semi-finished product, especially a pneumatic tyre, incorporating such a composite reinforcer.