The specification is concerned with a process and apparatus for continuous manufacture of moisture curable silicone compositions. The procedure comprises continuously introducing to the first mixing zone of a screw-extruder device the ingredients of a moisture curable organosiloxane composition comprising a silanol-terminated polyorganosiloxane containing at least two silanol groups per molecule, a curing agent consisting essentially of at least one silane containing at least 3 alkoxy groups per molecule, and a catalyst for the curing reaction which takes place in presence of moisture, subjecting the ingredients to the mixing and transporting action of the screw of the screw-extruder device for a period of time to effect mixing to homogeneity of the ingredients in the mixture, passing the mixture through a residence zone in which the mixture is not subjected to the mixing action of the screw of the screw-extruder device and in which residence zone the mixture is permitted to react for a period of time and transporting the composition through a second mixing zone from which volatile materials are exhausted from the mixture and extruding the mixture into storage containers.