Communication: The water soluble poly(ferrocenylsilane) polycation, poly(ferrocenyl(3-ammoniumpropyl)methylsilane), was synthesized by transition metal-catalyzed ring-opening polymerization of the novel [1]ferrocenophane Fe(eta -C5H4)(2)SiCH3(CH2)(3)Cl and by subsequent side group modification. Amination of the chloropropyl moieties using potassium 1,1,3,3-tetramethyldisilazide followed by acidic hydrolysis produced the polycation. The polycation was employed together with poly(sodium vinylsulfonate) in the electrostatic layer-by-layer self-assembly process to form organometallic multilayers on quartz. The multilayer fabrication process was monitored using UV/Vis absorption spectroscopy and XPS.