A new class of polysiloxane-block-polyimides having silicate in the polysiloxane segments were successfully synthesized and the thermal and mechanical properties of their crosslinking investigated using cast films. The silicate-containing copolyimides were easily derived by hydrosilylation of polysiloxane-block-polyimides having vinyl groups in the polysiloxane segments prepared from 3,3＇,4,4＇-benzophenone-tetracarboxylic dianhydride (BTDA), 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone (BAPSM) and several kinds of copolyimides with vinyl functionalized diamino-(poly)siloxanes accompanied by solution imidization. During hydrosilylation a small excess of diethoxy(methyl)silane was reacted using hydrogen hexachloroplatinate (H2PtCl6. 5H(2)O) as the catalyst. The copolyimides finally obtained were soluble in various organic solvents and easily hydrolysed to form crosslinked copolyimides during solution casting of films for investigation. The resulting materials have various potential applications as organic-inorganic hybrid materials.