The diffusion of the cation, the anion, and the polymer chain in the hydrated low molecular weight polymer electrolyte system LiCF(3)SO(3)PEG(10) has been studied by Li-7, F-19, and H-1 NMR, using the fringe field of a 7 T superconducting magnet. The self-diffusion coefficient for each species increases upon hydration. The increase is fast in the beginning but levels off at high concentrations of water. The ionic conductivity, measured by ac impedance spectroscopy, behaves in a similar fashion when the system is hydrated. The data show that the ions decouple from the polymer chain when water is added because of the water coordinating the cations and displacing the ether oxygens. This results in faster diffusion of the ions and an increase in the ionic conductivity. The measured ionic conductivity agrees well with that predicted by the Nernst-Einstein equation, by adding the contributions of the cations and the anions. The only exception is the dry sample, where ion pairing is important.