Graphene oxide (GO) modified Co-B catalysts for NaBH4 hydrolysis have been synthesized by the chemical reduction in this work. The structural features and catalytic performance of as-prepared samples have been investigated and discussed as a function of amounts of GO. According to structure characterization, the catalysts still retain the amorphous structure of Co-B alloy with the addition of GO, while GO exists as reduced GO (r-GO). The textural analysis and morphology observation indicate that the appropriate amount of GO in Co-B catalyst results in the obvious increase of specific surface area and uniform clustered morphology, which contributes to improve active surface area for catalytic reactions. The results of surface species characterization show that the electron density at active Co sites increases due to an electron transfer from B to Co facilitated by r-GO. It has been found that 50 mg GO modified Co-B catalyst exhibits especially high activity with a hydrogen generation rate of 14.34 L min(-1).g(catalyst)(-1) and much lower activation energy of 26.2 kJ mol(-1) for hydrolysis reaction of NaBH4. Meanwhile, the reusability evaluations show that the catalyst preserves high stability which can still maintain 81.5% of its initial activity after 5 catalytic cycles. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.