In this study, an improvement in the supercapacitive behavior of a symmetrical carbon-based supercapacitor is achieved by modifying the stainless steel current collector using platinum nanoparticles (PtNs). The PtNs are allowed to grow on the surface of the current collectors before they make contact with the surface of activated carbon electrode monoliths prepared from pre-carbonized rubber wood sawdust. All of the methods used in the present study, i.e., electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge–discharge tests provide consistent results, suggesting that the monolithic form of carbon electrodes and PtNs play a significant role in reducing the equivalent series resistance from 337 to 18mΩ and to increase the specific capacitance from 108 to 151Fg−1. This change improves the specific energy from 2.5 to 3.3Whkg−1 and the specific power from 275 to 288Wkg−1, respectively.