The first-time synthesis and use of poly (N-vinyl-2-pyrrolidone)-stabilized cobaltruthenium nanoclusters (4.1 +/- 1.2 nm) to produce pure hydrogen gas from hydrazine borane via hydrolysis is reported here. The cobalt-ruthenium nanoclusters are synthesized by co-reduction of water-soluble suitable cobalt and ruthenium salts in ethanol/water mixture by refluxing. They are characterized by advanced analytical techniques of transmission electron microscopy and UV-Vis and X-ray photoelectron spectroscopies. They are very stable and durable nanocatalysts found to be highly effective towards hydrogen evolution from hydrolysis of hydrazine borane at mild conditions. They provide 90 min(-1) of average turnover frequency value and 56.2 kJmol(-1) of activation energy for this catalytic hydrolysis of hydrazine borane. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.