The effect of lithium bis(oxalato)borate (LiBOB) on the physicochemical properties of lithium perchlolate solutions in sulfolane and the cycling time of lithium metal electrode is studied. It is found that the introduction of a small amount (0.24 M) of LiBOB into sulfolane solutions of LiClO4 increases insignificantly the solution viscosity but does not decrease the specific ion conductivity. The larger amounts of LiBOB decrease the electrolyte solution specific ion conductivity and increase both its viscosity and the activation energies of conductivity and viscous flow. The corrected conductivity of the solution containing two salts with the overall concentration 1.54 М is shown to far exceed the corrected conductivity of 1.5 М LiClO4 solution in sulfolane, which can be explained by the formation of ion associates of the higher order in the presence of LiBOB. The introduction of lithium bis(oxalato)borate into sulfolane solutions of lithium perchlorate increases the resistance of surface layers on the lithium metal electrode and the electrode cycling time. The main factor that determines the cycling time of lithium metal electrode is associated with protective properties of surface layers formed on the lithium electrode rather than with their conductivity.