The ionic diffusive motion (translational and rotational) of cations (NH4+ / H+) and anions (F-/BF4-) in polyethylene oxide (PEO) based polymer electrolytes containing ammonium fluoride (NH4F) and ammonium tetrafluoroborate (NH4BF4) has been studied by H-1 and F-19 NMR. Long range protonic translational motion has been observed at temperatures above the glass transition temperature (T-g)whereas rotational diffusion of fluoride has been observed in PEO-NH4BF4 at temperatures below T-g. In PEO-NH4BF4, both cations and anions have been found to show translational motion above T-g. (C) 2003 Elsevier B.V. All rights reserved.