The results of protons diffusion mathematical modeling in the crystalline lattice of NiOOH/ Ni(OH)2 are caparisoned with data of experiments on thin (100 μm) porous electrodes. The criterion of nickel hydroxide activity is offered as product of proton diffusion coefficient in the crystalline lattice of NiOOH on the square of specific surface area. It was founded existence of protons migration mechanism in a crystalline lattice under action electric field.
