A metallic or metallized reinforcer has at least a surface of which is at least partially metallic, the at least partially metallic surface being coated with a polybenzoxazine sulfide whose repeating units include at least one unit corresponding to formula (I) or (II):




in which the two oxazine rings are connected together via a central aromatic group, the benzene ring of which bears one, two, three or four groups of formula —Sx—R in which “x” is an integer from 1 to 8 and R represents hydrogen or a hydrocarbon-based group including 1 to 10 carbon atoms and optionally a heteroatom chosen from O, S, N and P. Such a reinforcement can be used for the reinforcement of a rubber article, in particular a motor vehicle tire.