Abstract: A strip gel that may be water-swellable and a slab gel are combined on a common support for two-dimensional electrophoresis, with the strip gel isolated from the slab gel by a fluid-impermeable and electrically insulting barrier, which is preferably one wall of an enclosure that forms a reservoir for containing the strip gel. The first dimension separation is performed by placing the liquid sample and buffer in the reservoir to cause the gel to swell and to load it with sample, then passing an electric current through the reservoir. The barrier, which is joined to the support in an easily breakable manner, is then removed, and the strip gel is placed in contact with the slab gel for the second dimension separation.