Atomistic molecular modelling has been utilized to construct a proton-conducting polymer electrolyte system consisting of poly(ethylene oxide) sulfonic acid anion (PEO sulfonic acid anion), water, hydronium ion and proton in an amorphous cell. The forcefield was parametrized to simulate proton transport as accurately as possible in an atomistic model. The coordination study was made and found to be mainly in accordance with experimental data. The diffusion coefficients for the PEO sulfonic acid anion, water, the proton and for the hydronium ion were determined. The ion conductivities of the whole system and of the ions were estimated and found to be in accordance with experimental values. The good correlation between the experimental and simulated results shows that the used model may provide guidance for evaluating new materials by experimentalists.