The mechanical proper-ties of fully dense, porosity-free nanocrystalline cobalt, prepared by the pulsed current electrodeposition technique, were determined by tensile testing. Considerable increases were observed in yield strength and ultimate tensile strength compared with conventional polycrystalline cobalt. On the other hand, Young's modulus was found to be little affected by grain size reduction. Surprisingly, the reduction in elongation to fracture with decreasing grain size was less severe as compared to previously reported values for nanocrystalline nickel prepared by the same method.