Preparation for passivating metallic surfaces, comprising at least one itaconic acid homopolymer or copolymer (A), water and/or another solvent suitable for dissolving, dispersing, suspending or emulsifying the homopolymer or copolymer (A), as component (B); at least one organic Ti or Zr compound (C); and optionally at least one Zn or Mg salt (D). Process for producing a passivating layer on a metal surface by treating the metal surface with such a preparation. Passivating layer on a metallic surface, obtainable by such a process. Metallic surface comprising such a passivating layer. Use of inventive preparations for passivating a metal surface.