Sodium borohydride (NaBH4) is an ideal chemical carrier of hydrogen due to its high hydrogen release capacity via hydrolysis, however the reaction is restricted by a competent catalyst. Herein, we present an efficient catalyst ultrafine non-noble Co nanoparticles supported on carbon nanospheres (CNSs) (CNSs@Co), for hydrogen generation from NaBH4 hydrolysis in alkaline media. The ultrafine Co nanoparticles distribute evenly over the surface of the CNSs by adjusting solubility of a by-product NaBO2 within ethanol. The as-prepared CNSs@Co catalyst has a glorious catalytic activity for hydrogen evolution of NaBH4. It shows a high hydrogen generation rate (HGR) of 7447 mL(H2):min(-1),gM(-1) at 30 degrees C, and a low activation energy of 40.79 kJ mol(-1). Besides, the catalyst exhibits a stable cycling capability in a consecutive cycling test. The outstanding catalytic performance of the CNSs@Co catalyst could attribute to the ultrafine size of the Co nanoparticles (similar to 7 nm) and its uniform dispersion supported by the CNSs. We believe the catalyst together with its synthetic method will provide a probable strategy to promote the hydrogen generation from NaBH4. (c) 2020 Elsevier Ltd. All rights reserved.