The microstructure and tensile properties were investigated for pulse-plated nanocrystalline nickel electrodeposits prepared from an additive-free sulfamate-based solution. Square-wave cathodic current densities were varied from 25 to 75 mA/cm2. The samples deposited at 25 mA/cm2 showed the smallest grain size (d ∼ 12 nm), and the grain size was found to increase with increasing current densities. The grain size of the electrodeposits ranged from approximately 27 to 12 nm. Tensile results indicated that the yield strength of the specimens increased with decreasing grain size. Scanning electron microscopy revealed that all electrodeposits fractured through a ductile mechanism.