The influence of different surface modifications of carbon supports on the corrosion resistance of 50 wt % Pt/C catalysts on their basis was studied. The corrosion resistance was measured from changes in the electroactive surface area of platinum in the course of potential cycling from 1.0 to 1.5 V versus the reversible hydrogen electrode (potential sweep rate, 0.5 V/s) during 60000 cycles. A 40% Pt/Vulcan XC-72 commercial catalyst was used as the reference sample. The supports were modified by the carbonization of the high surface area carbon black Ketjenblack DJ-600 and by the additional activation of the carbon-carbon composite Sibunit-1562. It was found that the preliminary carbonization of the Ketjenblack DJ-600 support with a propane-butane mixture at 770°C and the activation of Sibunit-1562 with subsequent thermal treatment at 500°C increased and decreased, respectively, the corrosion resistance of the 50 wt % Pt/C catalysts on their basis.