The diffusion coefficients of ions in the reverse transport system using the carrier mediated membrane were estimated from the diffusional membrane permeabilities and the ion activity in membrane system. In the aqueous alkali metal ions-membrane system diffusional flux of alkali metal ions driven by coupled proton was analyzed. The aqueous phase I contained NaOH solution and the aqueous phase II also contained NaCl and HCl mixed solution. The concentration of Na ions of both phases were $10^{0},;10^{-1},;10^{-2},;5{ imes}10^{-1};and;5{ imes}10^{-2};mol{cdot}dm^{-3}$ and the concentration of HCI in aqueous phase II was always kept at $1{ imes}10^{-1};mol{cdot}dm^{-3}$. Moreover, the carrier concentration in liquid membrane was $10^{-2};mol{cdot}dm^{-3}$. The results indicated that the diffusion coefficients depend strongly on the concentration of both phases electrolyte solution equilibriated with the membrane. The points were interpreted in terms of the energy barrier theory. Furthermore, eliminating the potential terms from the membrane equation was derived.