The variation of surface area of platinum–carbon material of hydrogen fuel cell electrodes in the presence of structure-modifying carbon nanotubes under long-term electrochemical action is studied. The method of cyclic voltammetric curves is used to study the specific features of the variation of platinum nanoparticle surface area by the hydrogen desorption in the hydrogen region and the charging current of electrical double layer in the double-layer potential region. The results are obtained separately for the electrodes on the cathodic and anodic sides.