In this work, a new diffusion coefficient model was developed by considering the physical meaning of diffusion-coefficient in Fick's law. It contains two parts: the characteristic length item and the diffusion velocity item. The former was related with the intermolecular distance. The latter was related with the potential energy, and then a new potential energy equation for the calculation of the diffusion velocity was proposed in the work. Literature data for 35 electrolyte solution systems, with temperature varying from 293.15 to 323.15 K, were correlated using the developed model. The total average relative deviation of predicted values with respect to experimental data is 1.01%. Compared with the traditional diffusion coefficient model, the developed model provides more reliable results, and the final equation with only three adjustable parameters is more easily applied in engineering practices. (C) 2018 Elsevier B.V. All rights reserved.