NEW MATERIAL:A compound expressed by formula I {R1 represents (substituted) monovalent hydrocarbon; X represents alkoxy or halogen; Y represents monovalent siloxanyl expressed by formula II [R2 represents (substituted) monovalent hydrocarbon; (p)≥1]; Z represents divalent siloxanyl expressed by formula III ((q) is 2-11); (n) is 0-2; (k) is 0-3; (l) is 0 or 1; (k) and (l) are not 0 at the same time and (k)+(2l)+(n) is 2 or 3}.

EXAMPLE: 1-(4-Vinylphenyl)ethyltris(trimethylsiloxy)-silane.

USE: A raw material for introducing a siloxane part to various organic polymers, a modifying agent and a raw material for gas-transmissive materials such as contact lenses, etc.

PREPARATION: Divinylbenzene expressed by formula IV is reacted with a hydrogenated organosilicon compound expressed by formula V in the presence of a palladium catalyst.