The coupling reaction of styrene with vinylsilanes catalyzed by ruthenium complexes was investigated. RuHCl(CO)(PPh3)3 (I) and RuCl(SiR3)(CO)(PPh3)2 (where R3 = Me3 (II), Me2Ph (III), (EtO)3 (IV)) were found to be efficient and selective catalysts for the formation of E-1-phenyl-2-silylethene and evolution of ethene. Stoichiometric reactions of styrene with the Ru−Si bonds of II−IV in argon and silylstyrene with the Ru−H bond in air (I*) as well as a MS study of the product of the deuterated styrene with vinylsilanes are convincing evidence for the mechanism of the process involving the migratory insertion of styrene into the Ru−Si bond (and vinylsilane into Ru−H bond) followed by β-H (and β-Si) elimination to give phenylsilylethene (and ethene). Kinetic tests (TOF) indicate a prior dissociation of the PPh3 molecule (or by its oxygenation) from I to yield pentacoordinated RuHCl(CO)(PPh3)2 which is almost as active as II.