Within the framework of the Joule III project a compact methanol reformer (CMR) with a specific weight of 2 kg/kW (lower heating value of H-2) was developed. This CMR contains a methanol and water vaporizer, a steam reformer, a heat carrier circuit and a catalytic burner unit. A laboratory fixed-bed reactor consisting of four tubes which could be filled with different amounts of catalyst was used to investigate the catalyst performance and the ageing behaviour. A hydrogen yield of 10 m(N)(3)/(h 1(Cat)) can be achieved at 280 degrees C. In this case, the methanol conversion rate is 95% and the dry product gas contains 0.9% CO. A linear decrease of the catalyst activity was observed which can be described by a loss of active catalyst mass of 5.5 mg/h. The catalyst was operated for more than 1000 h without having exhibited activity losses that made a catalyst change necessary. Besides, the stationary behaviour of the reforming reactor, the dynamic behaviour was studied. The time needed for start-up procedures has to be improved for reformers of a next generation. Moreover, the hydrogen production during reformer load changes will be discussed. Simulations of the power train in driving cycles show the different states of a reformer during dynamic operation.