A method was developed for the calculation of constant diffusion coefficients in particle diffusion controlled ion exchange. This method were often found adequate in spite of its theoretical dependence on ionic concentration as defined by Nernst-Planck equation. The diffusion coefficient was also found a function of the degree of exchange and a corrective scheme for such an effect was provided. Finally by defining the adequate average particle size of a group of particles, the rate constant for empirical rate equations was calculated.