We have developed a hydrogen generator that generates high purity hydrogen gas from the aqueous solution of sodium borohydride, NaBH4. This paper discussed the performance testing of the hydrogen generator using a Pt-LiCoO2-coated honeycomb monolith. The NaBH4 solution hydrolyzed to generate H-2 and sodium metaborate when it contacted the monolith. The gravimetric and the volumetric H? densities of the system were 2 wt.% and 1.5 kg H-2/100 1, respectively. The volumetric density was similar to that of the compressed H,) at 25 MPa. The hydrogen generator successfully provided a maximum H,) generation rate of 120 nl/min. Assuming a standard PEM (polymer electrolyte fuel cell, PEFC) fuel cell operated at 0.7 V, generating 120 nl/min was equivalent to 12 kW. (C) 2003 Elsevier B.V. All rights reserved.