An RTV organopolysiloxane composition comprises (A) an organosiloxane polymer comprising R3SiO1/2 units and SiO4/2 units in a molar ratio of 0.6-1.2 and having a hydroxysilyl content of 0.04-0.07 mole/100 g, (B) a polysiloxane having a hydrolyzable silyl group incorporated in the molecular chain via an alkylene linkage, (C) a hydrolyzable silane or its partially hydrolytic condensate having a boiling point of at least 150° C./101325 Pa, and (D) a cure catalyst. The composition remains stable during long-term storage. It has a low viscosity and good workability when heated, develops initial adhesion when allowed to cool after application, and thereafter cures at room temperature.