The carbon nanotube supported platinum nanoparticles prepared by the direct supercritical CO2 deposition method (Pt-CNT SC) has been quantitatively compared to two other methods of the catalyst synthesis. The physical appearance of the Pt-CNT SC was no different from the other catalysts according to the TEM images and the XRD patterns. The catalytic activity of the Pt-CNTs in the oxygen reduction reaction was tested by conducting the voltammetry and the Tafel analysis in 1.0 M H2SO4. The hydrodynamic voltammetry showed that 3.1 electrons were transferred in the Pt-CNT SC catalyzed oxygen reduction indicating that the reaction path was a series of H2O2 and H2O formation. The observed cathodic exchange current of the Pt-CNT SC was 0.705 µA/cm2. This indicates that the catalytic activity of the Pt-CNT SC was comparable to the Pt-CNT prepared by the hexane medium room temperature microemulsion method (0.749 µA/cm2) and was better than the commercial carbon black supported platinum catalyst (0.540 µA/cm2).