A new design for a microchannel methanol-steam reformer has been developed to provide power in conjunction with a micro fuel cell for a portable, low-power device. The design is optimized for low pumping power and rapid operation as well as thermal efficiency, overall size, and complete generation of the available hydrogen. An iterative, implicit, finite element solution code, which locates the boundaries between liquid, two-phase, and gaseous flow, provides a complete solution of the fluid and heat transfer properties throughout the device. The solution employs experimentally verified microchannel fluid dynamics relations to develop accurate results, but this is the first application of those relations to a methanol-water mixture. Based on this analysis, the proposed microreformer design will have an efficiency of 42%, with a theoretical maximum of 70%.