Hydrogen production from alkaline sodium borohydride (NaBH4) solution via hydrolysis process over activated carbon supported cobalt catalysts is studied. Activated carbons are used in their original form and after liquid phase oxidation with HNO3. The changes in surface functional groups of the activated carbon are detected by FTIR spectroscopy. The effects of HNO3 oxidation on the properties of the activated carbon and the resulting catalyst performance are investigated. FTIR analysis reveals that the oxidative treatment leads to the formation of various functional groups on the surface of the activated carbon. Cobalt catalysts supported on the modified activated carbon are found to exhibit higher activity and stability. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.