The effect of electoless-deposition time of a Co-P catalyst on the kinetics of H(2) generation in an alkaline NaBH(4) solution, and its cyclic durability are investigated. The electroless-deposited Co-P catalyst is composed of both outer spherical Co-P particles and an inner flat Co-P layer. As the deposition time of the Co-P catalyst is increased, the outer spherical Co-P particles grow, and their H(2) generation kinetics increase. However, the weight-normalized reaction rates differ as a function of deposition time, although the weight of the deposited material is proportional to the deposition time. Specifically, the Co-P catalyst deposited for 3 min shows the highest weight-normalized H(2) generation rate than those deposited for other lengths of time. The rate of H(2) generation for the Co-P catalyst is decreased dramatically after one cycle (10 h) due to separation of the Co-P particles from the Co-P plate. Up to the sixth cycle (60 h), the rate of H(2) gradually decreases due to a powerful shock on the catalyst support by expansion of H(2) volume. Beyond six cycles, the catalytic performance of the Co-P catalyst was stable enough for repetitive use. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.