Electrical dc conductance of a composite electrode for a lithium-ion battery was monitored in situ during successive charge/discharge cycles, in order to investigate functions of conductive additives. Such measurement was achieved by means of an interdigitated microarray electrode with a bipotentiostat. The composite films of mesocarbon microbeads (MCMBs) heat-treated at 1000 o C were studied with conductive additives of acetylene black or a synthetic graphite in a 1 M LiClO 4 non-aqueous carbonate solution. The role of the conductive additives is discussed in connection with their type and content within the composites. In addition, we propose a modified preparation procedure for the composites having a high retention of conductance.