We discuss key integration issues and engineering trade offs germane to all miniaturized fuel cell systems: thermal management, humidification control, water recirculation, air movement, fuel delivery, and power conditioning. We propose a design for a miniaturized. proton-exchange-membrane methanol-based fuel cell for powering 0.5-20 W portable telecommunication and computing devices. Our system is implemented on a silicon substrate to leverage advanced silicon processing and microelectromechanical systems technology enabling optimal fuel cell performance and minimizing production costs. We propose two alternative designs: a bipolar design using separate Si wafers for the anode and cathode and a monolithic design incorporating anode and cathode onto a single Si wafer.