An easy and simple method of one-step reaction was employed to synthesize the platinum-adsorbed polypyrrole nanocomposite (Pt-PPy). The prepared nanocomposite materials were characterized using UV-vis absorption spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and cyclic voltammetry. Polypyrrole within nanocomposite could crosslink to improve its stability on the Au substrates. O-2 reduction was performed at Au electrodes modified Pt-PPy in O-2-saturated 0.5 M H2SO4 solution. The results clearly show that modification of Pt-PPy nanocomposite results in the enhancement of the electrocatalytic reduction of oxygen. The nanocomposite may provide a novel electrode material for application in fuel cells and oxygen sensors.