A quantification of diffusion dialysis process in a single electrolyte system has been investigated in this study. Firstly, the volume of water which permeates from water side to feed side was to be quantified detailedly, and results showed that diffusate solution volume changes over time according with the characteristics of quadratic polynomial (y = a(0)tau(2) + b(0)tau + c(0)). Secondly, Permeability coefficients of membrane to H2O (P-H2O, P'(H2O)) and NaCl (P-NaCl, P'(NaCl)) were used to quantify diffusion dialysis process. Results showed that with the increase of feed concentration, P'(NaCl) and P-NaCl decrease, while P'(H2O), and P-H2O increase. Furthermore, when modifying factor lambda = 3.30 and theta = 2.37, comparisons of theoretical and experimental concentrations of NaCl in diffusate solution illustrated that both P'(H2O) and P'(NaCl) are satisfactory coefficients for characterizing the diffusion dialysis process. In addition, the mathematical model discussed in this study can provide an effective method to deal with the mass transfer process of diffusion dialysis easily and conveniently, especially, is helpful to select an optimum ion exchange membrane to operate diffusion dialysis. (c) 2012 Elsevier B.V. All rights reserved.