Grain size of CP–Ti sample after 7 cycles of accumulative roll bonding (ARB) reached to 80 ± 5 nm. Grain refinement in nano-scales led to a reduction in both corrosion and passive current densities. ARB process promoted formation of thicker and less defective passive film. Nano-grained CP-Ti is more suitable for implant applications compared to that of annealed CP-Ti.