Abstract: This invention discloses a method of controlling hydrosilylations in a reaction mixture by controlling the solution concentration of oxygen in the reaction mixture, relative to any platinum present in the reaction mixture. This invention further discloses a method for controlling isomerization in linear or branched alkenyl compounds having at least 4 carbon atoms during a hydrosilylation reaction by introducing a controlled amount of oxygen into the alkenyl compounds during the hydrosilylation. This invention further discloses a method for producing dicycloalkylsubstituted silanes by reacting a halo-or alkoxy-silane with a unsaturated cycloalkenyl compound in the presence of oxygen and a hydrosilylation catalyst.