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 H2 and sodium metaborate when it contacted the monolith. The gravimetric and the volumetric H2 densities of the system were 2wt.% and 1.5kg H2/100l, respectively. The volumetric density was similar to that of the compressed H2 at 25MPa. The hydrogen generator successfully provided a maximum H2 generation rate of 120nl/min. Assuming a standard PEM (polymer electrolyte fuel cell, PEFC) fuel cell operated at 0.7V, generating 120nl/min was equivalent to12kW.