The resistance to electrochemical oxidation of carbon black (Vulcan XC-72) and chemical vapor deposited multiwalled carbon nanotubes (CVD-MWNTs), both widely-used as catalyst supports for low temperature fuel cells, is investigated with potentiostatic oxidation in 0.5 mol L-1 H2SO4, which mimics the working conditions of low temperature fuel cells. The surface oxygen of oxidized carbon black and MWNTs are analyzed with cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). The increase in surface oxygen on MWNTs during 120 h holding at 1.2 V (versus Reversible Hydrogen Electrode, RHE) is much less than that on carbon black. The conclusion can be reached that CVD-MWNTs are more resistant to electrochemical oxidation than carbon black under the condition in the report. CVD-MWNTs therefore possess a higher potential for low temperature fuel cell applications. (c) 2006 Elsevier Ltd. All rights reserved.