The path of the silica/organosilane reaction and its dependence on various material and reaction parameters is investigated by determining the amount of ethanol evolved during rubber compounding. The results found on model systems which were based on the principle of comparing the chemical reactions of related systems are applied to practical rubber compounding. They ave then used to interpret and understand the data obtained. The multiplicity of possibilities which ave able to influence the silica/organosilane reaction and in-rubber data become apparent.