In this paper a new, continuously operated, radially symmetric electrophoresis device is presented, which is intended for preparative application in downstream processing of biological products. Due to the small separation distance of at most a few millimeters, Joule heating can be neglected. The accelerated, inward directed flow contributes to the suppression of turbulence and free convection. A detailed description of the design of the apparatus is followed by a discussion of the two-dimensional flow pattern and the protein trajectories within the electric field. A sample stream of 400mL/h containing three proteins (BSA, myoglobin and cytochrome c) was processed, yielding an almost complete separation of the three components with high values of purity and recovery. Investigations of the possible maximal throughput and different band broadening effects are discussed. (c) 2005 Elsevier Ltd. All rights reserved.