This paper describes the design, realisation and test of a power unit based on a polymer electrolyte fuel cell, operating at room temperature, for portable application. The device is composed of an home made air breathing fuel cell stack, a metal hydride tank for H2 supply, a dc–dc converter for power output control and a fan for stack cooling. The stack is composed by 10 cells with an active surface of 25cm2 and produces a rated power of 15W at 6V and 2A. The stack successfully runs with end-off fed hydrogen without appreciable performance degradation during the time. The final assembled system is able to generate 12W at 9.5V, and power a portable DVD player for 3h in continuous. The power unit has collected about 100h of operation without maintenance.