Poly[p- and m-(methylsilylene)phenylenes] were prepared from the reaction of dichloromethylsilane with p- and m-dilithiobenzene in 11% and 31% yields, respectively. The reaction of dichlorophenylsilane with p-dilithiobenzene afforded poly[p-(phenylsilylene)phenylene] in 58% yield, while treatment of bis(chlorosilyl)benzene with p-dilithiobenzene gave poly[p-(silylene)phenylene] in 15% yield. These polymers readily react with olefins and acetylenes in the presence of a platinum catalyst to give hydrosilation products. Thermal behavior of the polymers and poly[p-(dimethylsilylene)phenylene] prepared from p-phenylenedimagnesium dibromide with dichlorodimethylsilane was also investigated by thermogravimetric analysis in air as well as in a nitrogen atmosphere.