Abstract: A process for producing organosilicon compounds of the formula (RO)3-mRmSi—Alk—Sn—Alk—SiRm(OR)3-m in which R is a monovalent hydrocarbon having 1-12 carbon atoms, Alk is a divalent hydrocarbon having 1-18 carbon atoms, m is 0, 1 or 2, and n is 2-8, preferably 3-8. The process consists generally of the steps of (I) heating and reacting (A) a sulfide compound such as M2Sn or MHS where H is hydrogen, M is ammonium or an alkali metal, and n is 1-8; with (B) a silane compound of the formula (RO)3-mRmSi—Alk—X where X is Cl, Br or I, and m is 0, 1, or 2; and with (C) sulfur. Step (I) is carried out in the presence of a phase transfer catalyst, and an aqueous phase containing a buffer or a basic compound, to form a product mixture. In step (II), the product mixture is again heated to a temperature of 80-100° C., preferably a temperature of 85-95° C., and most preferably to a temperature of 87-92° C.