Dehydrogenative condensation of trihydrosilanes is catalyzed by (C5Me5) 2NdCH (SiMe3) 2 to give polysilanes in high yields. In the polymerization of PhSiH3, molecular weight of the polymer becomes higher with an increase of the reaction temperature. Cyclic structures are indicated for oligomers larger than pentamers by FD-MS spectroscopy.