A membraneless microfluidic fuel cells that exploit laminar flow at the microscale to separate the fuel and oxidant streams is presented. Because the streams mix only by diffusion, fuel and oxidant streams of different pH can be used such that the anode and cathode both operate at their optimal pH. One issue with biofuel cells, however, is the fact that different enzymes have optimal activity at different pH. Using a fixed pH electrolyte may maximize the enzyme activity at one electrode while resulting in poor enzyme activity (or even denaturing of the enzyme) at the electrode. An experiment in designing and operating laminar flow biofuel cells that are run using alcohol and oxygen, with buffered alcohol solution (pH ∼ 7) and aqueous sulfuric acid solution (pH ∼ 0) as the anolyte and catholyte, respectively, is presented. This is an abstract of a paper presented at the 2005 AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).