Electrochemical performance of activated carbon/sulfur composite cathode in the Li-S cell with standard and TiO2-modified separator is evaluated by cyclic voltammetry and galvanostatic chronopotentiometry. The modification of the separator by TiO2 impregnation has beneficial effect on the charge capacity of the activated carbon/sulfur cathode in the Li-S cell. The specific capacity of the cathode in the cell with TiO2-modified separator is 632 mAh g-1 (calculated from cyclic voltammetry) and 673 mAh g-1 (determined from galvanostatic chronopotentiometry). Facile impregnation of the separator with nanocrystalline TiO2 results in the 10-20 % stable increase of the charge capacity of corresponding activated carbon/sulfur cathode as compared to its electrochemical performance in the system with non-modified separator.