Nanocrystalline nickel electrodeposits were fabricated at 18, 25 and 50 mA cm(-2) using a sulfamate-based electrolyte. The crystallite size of the deposits was evaluated by XRD technique and their mechanical properties were characterized by tensile testing. The results of this study confirmed that increasing the current density results in an increase in the grain size of nickel deposits. The strength of the deposits decreased consistently with increasing the crystallite size. However, the deposit fabricated at 50 mA cm(-2), in comparison to nickel with conventional grain size (> 1 mum), showed a relatively low strength and a surprisingly low tensile elongation. It is suggested that the enhanced evolution of hydrogen at high current densities is responsible for the formation of larger crystals and the unusual low tensile elongation.