Measurements of the electrical conductivities of three types of polysilanes were carried out over a range of de fields and temperatures. These polymers are varied in substituents and structures with formulas of [C6H5SiCH3](n), [(C6H5SiCH3)(70)(CH3SiH)(30)](n), and [(C6H5SiCH3)(50) (C6H5SiH)(30)(CH3Si)(20)](n). Undoped polysilanes behaved as insulators since their conductivities were observed in the range of 10(-10) to 10(-13) S cm(-1), while SbF5-doped polysilanes of all kinds behaved as semiconductors with conductivities in the range of 10(-2) to 10(-4) S cm(-1). No significant difference in conductivities was observed among three SbF5-doped polysilanes although these polymers are very different in chemical properties. These experimental results suggest that electrical conductivities of polysilanes are associated with the Si-Si main-chain backbone rather than with the side groups. It is evident that the dopant is able to diffuse throughout the bulk of the polymer and the conductivity of the doped polymer is a function of the dopant concentration from the result of in situ monitoring of the resistance of the silane homopolymer during SbF5 doping at room temperature. The conductivities of polysilanes appeared to be temperature-dependent. The activation energy for the conduction of SbF5-doped silane copolymer was found to change at its glass transition temperature.