Composite reinforcement (R-2) that is self-adhesive by curing to a diene rubber matrix, which can be used as reinforcing element for a tire, comprising: one or more reinforcing thread(s) (20), for example a carbon steel cord; a first layer (21) of a thermoplastic polymer, the glass transition temperature of which is positive, for example 6,6 polyamide, covering said thread or said threads; and a second layer (22) comprising a functionalized unsaturated thermoplastic stirene elastomer, the glass transition temperature of which is negative, for example an epoxidized SBS elastomer, covering the first layer (21), said elastomer containing functional groups selected from epoxide, carboxyl and acid anhydride or ester groups. Process for manufacturing such a composite reinforcement and rubber article or semi-finished product, especially a tire, incorporating such a composite reinforcement.