An open electrolytic cell has been designed and constructed for use in a dry environment. This was used to investigate the passivation processes concerned with both the lithium and the carbon (SO2) electrodes. A.c. impedance techniques have been used in both two and three terminal cell systems in order to study the kinetics of the electrode processes. Effects of temperature, state-of-charge and reverse cell operation have been studied. Computer simulations were made of the growth of crystals on a flat (Li) surface and the resulting growth transients connecting current and time were derived. This model was extended to simulate the porous carbon (SO2) electrode and the utilisation of the carbon as a function of the depth of reaction penetration into the electrode is devised for both potentiostatic and galvanostatic discharging.