Intrazeolite cobalt(0) nanoclusters were prepared by ion-exchange of Co2+ ions with the extraframework Na+ ions in the zeolite-Y followed by the reduction of Co2+ ions in the supercages of zeolite-Y with sodium borohydride at room temperature. The intrazeolite cobalt(0) nanoclusters were isolated as solid materials and characterized by ICP-OES, XRD, HRTEM, SEM, XPS, Raman spectroscopy and N-2 adsorption technique. The catalytic activities of intrazeolite cobalt(0) nanoclusters in the hydrolysis reaction of sodium borohydride solution in the absence or presence of added base were studied. They are found to be more active in basic solution than in aqueous solution without added base. They provide 36,000 total turnovers and a turnover frequency up to 880 mol H-2 (mol Co)(-1) h(-1) in the hydrolysis of basic sodium borohydride solution at 2 5.0 +/- 0.1 degrees C. The improved hydrogen generation rate, hydrogen generation efficiency, lower activation energy and the low cost make the intrazeolite cobalt(0) nanoclusters promising candidate as catalyst for the hydrogen generation from basic sodium borohydride solution. (C) 2009 Published by Elsevier B.V.