In this study, conductive polyurethane (PU) films were prepared by the condensation of poly(propyleneglycol) (PPG), toluene 2,4-diisocyanate, and 3-methylthiophene (3-MT) under various preparation conditions. The immersion of the film in an organic solution of ferric chloride (FeCl3)/ethyl acetate led to the rapid formation of the conductive poly(3-methylthiophene) (PMT) layers via the diffusion-oxidative reaction of 3-MT and ferric chloride. We found that the electrical conductivity and the mechanical properties were affected significantly by the time, the FeCl3 concentration, the weight ratio of the 3-MT to PU, and the temperature of the diffusion-oxidative reaction. The effects that the reaction time and temperature have on the morphology and surface free energy were investigated by scanning electron microscopy (SEM) analysis and contact angle measurements, respectively. The mechanical properties, such as tensile strength and elongation at break, were also studied. The conductivity of the composite was as high as 42 S/cm.