Hybrid nanocomposites containing Pt nanoparticles (nano-Pt) and poly(3-methylthiophene) (P3MT) nanorods at glassy carbon surfaces have been successfully prepared by use of an in situ cyclic voltammetry (CV) method. Field emission scanning electron microscope (FE-SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltagrams were used to characterize the properties of these nanocomposites. SEM images showed that nano-Pt were located on the surface of P3MT nanorods and that they formed a three-dimensional (3D) porous nanostructure. EIS and CV results demonstrated that these hybrid nanocomposites had good conductivities, and could accelerate the electron-transfer rates of redox ions. From the results of electrochemical oxidation of methanol and nitrite, we observed that this nanocomposite-modified electrode exhibited excellent electrocatalytic activity, which might be useful in biosensors and/or fuel cells. (C) 2010 Elsevier Ltd. All rights reserved.