Molecular dynamic simulation models have been developed to investigate microscopic transport processes in Nafion polymer electrolyte. The diffusivity of methanol, water, hydronium, and proton in Nafion and the conductivity of Nafion were evaluated in a wide range of temperatures from 20 to 120°C for various water contents (λ=3.0, 13.0, and 22.0). In order to validate the simulation results, the conductivity of Nafion was evaluated using a four-probe conductivity measurement apparatus at temperatures from 20 to 120°C and at relative humidity from 30 to 100%. The permeability of methanol in Nafion was evaluated using a high temperature membrane diffusion cell. The differences between calculated conductivity results and measurement results were within 10% at room temperature but gradually increased with temperature. Computational permeability results were in good agreement with the experimental results within the confidence intervals. copyright The Electrochemical Society.