PURPOSE: To obtain an organopolysiloxane having bifunctional terminal siloxane units by using a method which is simple and selective, and is practicable with no costly purification steps.

CONSTITUTION: An organopolysiloxane of formula I [wherein R is a 1-18C hydrocarbon group; R1 is a 6-15C hydrocarbon group having at least one phenyl ring; R2 is a 1-3C hydrocarbon group; X is H or a divalent organic or organosilicon group bonding through a 2-15C hydrocarbon group which may be substituted; (a) is an integer of at least 1; (b), (c), (d) and (e) are each 0 or a positive integer; and the sum of (a), (b), (c), (d) and (e) is at least 3] is obtained. The organopolysiloxane of formula I where X represents a hydrocarbon atom is obtained by reacting an organopolysiloxane of formula II with at least one molar equivalence of a silane of formula III (wherein R, R1, R2 and a-e are the same as above) per one mole of the hydroxyl groups in the presence of a catalytic amount of a hydrosilation catalyst while liberating water.