Bipolar designs for a direct methanol fuel cell (DMFC) with liquid electrolyte have been investigated, aiming at a reduction of methanol crossover. A "spacer" (separator) material has to be applied which is inert in a sulphuric acid/methanol surrounding. This material has to be porous so that the liquid electrolyte can be pumped through. Swelling characteristics as well as variation of material properties with temperature and pressure have been investigated with several materials. It is essential to minimize the internal cell resistance in order to achieve a good performance of the DMFC. Due to the importance of electrolyte canal thickness with respect to ohmic resistance of the cell assembly, the variation of cell power output with electrolyte canal thickness was investigated. (c) 2005 Elsevier B.V. All rights reserved.