The rates of particle diffusion between calcium-form ion exchanger containing micro-component Co (Ⅱ) and calcium chloride solution, between cobalt-form ion exchanger and calcium chloride, magnesium chloride and barium chloride solutions and between calcium-form ion exchanger and cobalt chloride solution have been measured. It was found that the rate of ion exchange depends on the migration of individual ions and that the partitle diffusion coefficient changes with the fractional attainment of equilibrium.