PURPOSE: To obtain a (β-cyanoalkyl)organooxysilane that is useful as an intermediate by bringing β-cyanoalkylchlorosilane into contact with an alcohol in its film form and evaporating hydrogen chloride liberating as a by-product of the reaction.

CONSTITUTION: β-Cyanoalkylchlorosilanes represented by the formula (R is H, a (substituted) 1-12C monovalent hydrocarbon; Y is H, a 1-12C monovalent alkyl; a is 1-3; b is 0-2; a+b is 1-3) is brought into contact with silicon atom and an alcohol, preferably methanol or ethanol to form (β-cyanoalkyl) organooxysilane and hydrogen chloride. Then, hydrogen chloride is evaporated off from the film to recover the objective substance.