Abstract: Palladium nanoparticles stabilized with tris-imidazolium tetrafluoroborates catalyze the stereoselective hydrosilylation of internal alkynes in a dry inert atmosphere to give (E)- vinylsilanes in excellent yields. In the presence of controlled amounts of water a transfer hydrogenation reaction takes place with the formation of (Z)-alkenes or the corresponding alkanes. Keywords: alkynes; hydrosilylation; imidazolium salts; nanoparticles; palladium; ...