Organosilane polymers of the type [R₁ R₂Si]_n were prepared by dechlorination of R₁ R₂SiCl₂ (R₁ = CH₃; R₂ = H, C₂H₅, C₃H₇, C₄H₉, C₆H₁₁, C₈H₁₇ or C₆H₅) with sodium in toluene as solvent. The polymers were characterized by i.r., NMR and thermal analysis. The decomposition temperature, yield, solubility, appearance were found to depend strongly on molecular structure. The pyrolysis of polymethylsilane was found to give a 60% ceramic yield after thermal processing at 750°, suggesting its potential for use as a precursor to SiC ceramics.