The first high molecular weight polystannanes, H(SnR(2))(n)H (R = (n)Bu, (n)Hex, (n)Oct), result from dehydropolymerization of secondary stannanes R(2)SnH(2) by zirconocene catalysts. Good catalysts include zirconocenes based on both CpCp*Zr (Cp* = eta(5)-C(5)Me(5)) and Cp(2)Zr fragments, and the most active catalyst with respect to production of high molecular weight polystannanes was Me(2)C(eta(5)-C5H4)(2)Zr[Si(SiMe(3))(3)]Me. The latter catalyst produced H(Sn(n)Bu(2))(n)H chains (M(w)/M(n) = 66 900/20 300) that were contaminated by ca. 18% (by weight) low molecular weight cyclic oligomers. Lower molecular weights resulted from dehydropolymerizations of Me(2)SnH(2), PhMeSnH(2), and Ph(2)SnH(2). At room temperature, H(SnR(2))(n)H (R alkyl group) polystannanes have lambda(max) values at ca. 380-400 nm, attributed to sigma --> sigma* transitions. Thermal gravimetric analyses on the polystannanes reveal that these polymers are as thermally stable as related poly(dialkylsilane)s and have onset temperatures for thermal decomposition in the range 200-270 degrees C, under both nitrogen and air. The H(Sn(n)Bu(2))(n)H polymer has been shown to be a good precursor to SnO2, as shown by bulk pyrolysis in air (ceramic yield : 56%). Preliminary results also indicate that these polymers may be useful as precursors to elemental tin. The polystannanes are photosensitive, and erized by UV-vis spectrometry and Sn-119 NMR spectroscopy, which demonstrated that H(Sn(n)Bu(2))(n)H is photochemicaly depolymerized to a 2:1 mixture of cyclo-(Sn(n)Bu(2))(5) and cyclo-(Sn(n)Bu(2))(6). The polymers H(Sn(n)Hex(2))(n)H and H(Sn(n)Oct(2))(n)H exhibit thermochromic behavior which is visibly evident as a discoloration from yellow to colorless upon warming above room temperature. : 56%). Preliminary results also indicate that these polymers may be useful as precursors to elemental tin. The polystannanes are photosensitive, and erized by UV-vis spectrometry and Sn-119 NMR spectroscopy, which demonstrated that H(Sn(n)Bu(2))(n)H is photochemicaly depolymerized to a 2:1 mixture of cyclo-(Sn(n)Bu(2))(5) and cyclo-(Sn(n)Bu(2))(6). The polymers H(Sn(n)Hex(2))(n)H and H(Sn(n)Oct(2))(n)H exhibit thermochromic behavior which is visibly evident as a discoloration from yellow to colorless upon warming above room temperature.