Electrical and microstructural properties of the passive layers formed on lithium in SOCl2 containing different additives (PVC, inorganic salts, cathode additives) were studied. LiCl crystals were found to be cubic, octahedral or needle-like. Typical passive layer thicknesses were 1-20 mum. The electrical properties of the passive layer were explained by referring to the space charge model of SEI conduction. It was pointed out that impedance spectroscopy may be selectively used as a non-destructive method for estimation of the galvanostatic behaviour of lithium batteries. The best results, as regards the elimination of the delay effect, were obtained with a combination of organic and inorganic electrolyte additives.