In the pursuit of the development of alternative mobile power sources with high energy densities, this study elucidated a new hydrogen generation approach from solid NaBH4 using a new catalyst, sodium hydrogen carbonate (NaHCO3), which was placed in a small and compact cartridge. A planar air-breathing PEMFC system fitted with the cartridge has been investigated for testing hydrogen generation from NaBH4 and NaHCO3. NaHCO3 allowed the hydrogen cartridge to control hydrogen generation and to improve the power density, fuel efficiency, energy efficiency, and cell response. The cell performance of solid NaBH4 air-breathing PEMFC system strongly depended on the operating conditions: the feeding rates and concentrations of catalytic solutions for NaBH4 hydrolysis. In various concentrations (5 - 12 wt %) of NaHCO3 aqueous solutions, 10 wt % NaHCO3 aqueous solution exhibited the highest maximum power density of 128 mW cm(-2) at 0.7 V, which was estimated to be a Faradic efficiency of 78.4% and an energy efficiency of 46.3%. The data illustrated that NaHCO3 was an effective catalyst for hydrogen generation with the solid NaBH4, which is considered as a hydrogen carrier for air-breathing micro PEMFCs operated without auxiliary hydrogen controller or devices. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.