PURPOSE: To efficiently obtain silicon tetrachloride, by reacting colloidal silica soln., sodium silicate soln. or powdered material contg. silicon dioxide, and carbon fine powder with chlorine in the presence of potassium compd., as catalyst.

CONSTITUTION: The targeted silicon tetrachloride is obtd. by reacting colloidal silica soln., sodium silicate soln. or powdered material contg. silicon dioxide and carbon powder with chlorine in the presence of the catalyst consisting of potassium compd. As the colloidal silica soln. to be used, there are, for example, colloidal silica soln. recovered from hot water contg,. silici acid, synthetic colloidal silica soln., etc., of these solns., the soln. contg. 1W50wt.% SiO2 having 50W800 particle size, in a solvent such as water, methanol, ethanol, propanol, butanol, acetone can be suitably used. As the potassium compd. used as catalyst, inorg. acid salt (e.g., KHSO4), org. acid salt (e.g., CH3COOK), org. potassium compd. (e.g., C2H5OK), the compd. contg. fluorine atom (e.g. KF, sulfide (e.g., K2S), etc., are exemplified.