A system involving amorphous LiCl(PEO)(x) for x = 20, 35 and 50, and a 14 Angstrom diameter Al2O3 'Filler' particle has been simulated at nominal temperatures 290 and 330 K by the molecular dynamics method. The mobility of Li-ions is found to increase on the addition of the nanoparticle at 330 K and Li:EO ratio 1:50, but decreases or remains unchanged at other temperatures and concentrations. Lower temperature and concentration are generally associated with a lower Li-Cl coordination number and a correspondingly higher number of unpaired/unclustered ions in the system. A number of free Li+ ions and some Li-Cl pairs/clusters are found in an immobilised poly(ethylene oxide) (PEO) 'coordination sphere' around the nanoparticle. This reduces the number of Li+ ions in regions away from the particle surface. The number of 'free' Li+ ions away from the particle surface is largest for the intermediate composition x = 35 and at 290 K (similar to23% of the total number of lithium ions in the system); smaller for x = 50 ( similar to11% at both temperatures), and even smaller at x 20 (similar to5% at 290 K and similar to9% at 330 K). (C) 2003 Elsevier Science Ltd. All rights reserved.