Abstract: An electrophoretic gel cooled cell including a gel supporting surface. The cell includes members for holding gels against the supporting surface such that gels of either of two dimensions may be used with the cell. A reservoir adapted to hold a cooling medium shares a common wall with the supporting surface to cool the gel retained by the members. The reservoir has a large opening which may be closed by a cover for easy insertion and removal of the cooling medium from the reservoir. A venting valve in the reservoir cover vents gas in the reservoir to atmosphere and closes when the cover is in an inverted position to prevent condensate leakage through the vent.