A borated benzoxazine compound, which can be used in particular as monomer in the synthesis of polybenzoxazine, corresponds to the formula: in which: Z represents an at least divalent, aliphatic, cycloaliphatic or aromatic, bonding group comprising at least one carbon atom and optionally at least one heteroatom chosen from O, S and P; and R1, R2, R3 and R4, which are identical or different, represent hydrogen or an alkyl comprising from 1 to 12 carbon atoms, it being possible for R1 and R2, on the one hand, and R3 and R4, on the other hand, optionally to form a heterocycle with the two oxygen atoms and the boron atom to which they are respectively bonded.