A series of microfuel cell DMFC prototypes in the 1-2 W range has been developed at Motorola Labs. Design criteria, technical issues and the solution to those issues, system and component performance criteria are all discussed in detail with regards to the demonstrated systems. In particular, the industry-wide problem of long-term voltage degradation is explored with the implementation of a successful engineering solution to this issue which resulted in over 1200 h of system lifetime at the average degradation rate of 41 muV/(h per cell). With sufficient fuel for 1 week of continuous operation, the system energy density in the 2 W DMFC prototype was 490 Wh/kg and 368 Wh/L, respectively, at an overall system efficiency of 20% (includes both fuel conversion and BOP efficiencies). (C) 2004 Elsevier B.V. All rights reserved.