A series of high,molecular weight poly(ferrocenylgermanes) [Fe(eta-C(6)H(3)X)(2)GeR(2)](n) 5a-d (X = H; a, R = Me; b, R = Et; c, R = n-Bu; d, R = Ph) and 7 (X = SiMe(3), R = Me) were synthesized via the thermal ring-opening polymerization of the corresponding germanium-bridged [1]ferrocenophanes 4a-d and 6. Poly(ferrocenyldimethylsilane)-poly(ferrocenyldimethylgermane) random copolymer 8 was obtained by the thermal and transition metal-catalyzed ring-opening polymerization of a mixture of the [1]germaferrocenophane [Fe(eta-C5H4)(2)GeMe(2)] (4a) and the corresponding [1]silaferocenophane [Fe(eta-C5H4)(2)SiMe(2)] (2a). The molecular weights for the home- and copolymers were estimated by gel permeation chromatography in THF versus polystyrene standards and were found to be in the range of M(W) = 5.0 x 10(4)-2.0 x 10(6) and with polydispersities in the range of M(W)/M(n) = 1.2-2.4. A low-angle laser light scattering study of 5a in THF gave an absolute value of M(W) of 3.3 x 10(6), which was significantly greater than the GPC estimate (M(W) = 8.2 x 10(5)). Polymer thermal transition behavior and morphology were investigated by differential scanning calorimetry (DSC) and wide-angle X-ray scattering(WAXS). Glass transitions (T-g) for the polymers were in the range of -7 to +128 degrees C and were found to be strongly dependent on the size and nature of the substituents attached to germanium and the substitution of the cyclopentadienyl rings. The semicrystalline nature of the poly(ferrocenyldialkylgermanes) Sa-e and the copolymer 8 was apparent from the appearance of several fairly sharp diffraction peaks in the WAXS profiles of these polymers and the presence of melt transitions (T-m) in the DSC thermograms. In contrast, polymers 56 and 7 were found to be amorphous. Cyclic voltammetry of the polymers showed the presence of two oxidation waves, which is consistent with the presence of redox coupling arising from significant interactions between the iron centers. UV/visible spectra of polymers 5a-c, 7, and 8 were measured in THF in the 350-800 nn range and were found to be consistent with an essentially localized electronic structure for the polymer backbone.