The Potential step measurements are carried out on single beads of nickel hydroxide and the results are interpreted with a dual structure model featuring fast and slow diffusing components.The intrinsic diffusion coefficients for the two components are found to be in the order of magnitude 10-7 and 10-13～10-14 cm2s-1, respectively, with an apparent value for the slow component in the order of 10-10 cm2s-1.