Various factors of the influence of carbon matrices on the textural, structural, and electrochemical properties of nanocomposites based on highly dispersed carbon black after the thermal-oxidative action of steam are considered. The results of the measurements of the electrical resistance of nanocomposites with coke-pitch and pyrocarbon matrices and the testing of these materials by cyclic voltammetry in a two-electrode Swagelok cell with an aqueous electrolyte are given. An optimal ratio between a pyrocarbon matrix and carbon black, at which the specific capacity of the electrode reached a maximum and was comparable with the values for active carbon–based electrodes widely used in world practice, was established.