Electronic devices show an ever-increasing power demand and thus, require innovative concepts for power supply. For a wide range of power and energy capacity, membrane fuel cells are an attractive alternative to conventional batteries. The main advantages are &#x02022; the flexibility with respect to power and capacity achievable with different devices for energy conversion and energy storage, &#x02022; the long lifetime and long service life, &#x02022; the good ecological balance, &#x02022; very low self-discharge. Therefore, the development of fuel cell systems for portable electronic devices is an attractive, although also a challenging, goal. The fuel for a membrane fuel cell might be hydrogen from a hydride storage system or methanol/water as a liquid alternative. The main differences between the two systems are &#x02022; the much higher power density for hydrogen fuel cells, &#x02022; the higher energy density per weight for the liquid fuel, &#x02022; safety aspects and infrastructure for fuel supply for hydride materials. For different applications, different system designs are required. High power cells are required for portable computers, low power methanol fuel cells required for mobile phones in hybrid systems with batteries and micro-fuel cells are required, e.g. for hand held PCs in the sub-Watt range. All these technologies are currently under development. Performance data and results of simulations and experimental investigations will be presented.