The key characteristics of microfluidic fuel cell incorporated with an air-breathing gas-diffusion electrode were described. The performance of direct methanol laminar flow-based fuel cells (LFFC) with gas diffusion electrodes in acidic and alkaline media was compared. These cells exhibited high open circuit potentials of 0.93 and 1.05 v in acidic and alkaline media, respectively, which demonstrate control over methanol crossover in these fuel cell designs. A higher maximum power density of 17.2 mw/cm2 was obtained when operating in alkaline media compared to 11.8 mW/cm2 in acidic media. The cathode and anode exhibited better kinetics in alkaline solutions, in accordance with previous electrochemical studies in literature. These LFFC, however, avoided clogging of membrane pores by carbonate formation in alkaline media. This is an abstract of a paper presented at the 2006 AIChE Spring Annual Meeting (Orlando, FL 4/23-27/2006).