Abstract: A polymerization autoclave for the suspension polymerization of vinyl compounds in the aqueous phase having a volume of from 50 to 200 m.sup.3, an impeller agitator driven from below at the bottom of the autoclave and two cylindrical displacement bodies acting as flow interrupters, secured downwardly from the autoclave dome, where the autoclave has a height-to-diameter ratio of from 2.4 to 3 with a critically dimensioned agitator and critically dimensioned flow interrupter fittings. By the use of this invention in the case large-scale autoclaves, the heat of polymerization can be removed merely by wall-cooling. The autoclave according to the invention are very economical, as shown by, for example, a spatial capacity of 0.3 to 0.4 metric tons of polyvinyl chloride per m.sup.3 autoclave volume.