A device for the preparation of polyacrylamide tube gels for pore gradient gel electrophoresis is described. The glass tubes are arranged in the shape of a hollow cylinder, of which the outer as well as the inner surface can be cooled. By this arrangement, the maximum distance the heat of reaction has to be conducted is 7.5 mm. According to the outer diameter of the tubes, the number of gels held by one device ranges from 125 (5 mm) to 500 (2.5 mm). The gels are demonstrated to be identical, and allow for highly reproducible separations.