The nickel (Ni) nanocrystals (average diameter 9.7 +/- 2.3 nm) were deposited onto composite graphite electrode from a plating solution of 5.0 mM NiCl2 center dot 6H(2)O and 1.0 M NH4Cl using scan rate of 6500 mV s (1). The initial potential -1.5 V and final potential -0.5 V vs. Ag/AgCl with applied time 120 s were used for the whole deposition process. The variations of applied overpotentials and deposition times have affected the characteristics of Ni nanocrystals. It was found that the structural formation of Ni nanocrystals obtained were almost pure hexagonal close-packed (hcp). This study has demonstrated that the tuning of the final size, morphology and structural formation of the Ni nanocrystal were affected by control of nucleation, growth and hydrogen evolution processes in fast scan voltammetry technique used. (C) 2009 Elsevier Inc. All rights reserved.