Thermally stimulated currents from positively corona‐charged polypropylene films which were heat treated at various temperatures have been studied in the temperature range 20–165 °C. Three peaks are observed in the TSC spectra. Intensities of these peaks strongly depend on the thermal history of the sample films. A thermal effect of the TSC, which has been introduced during vacuum deposition of metallic electrodes on the sample films, is demonstrated. Observed results suggest that the electrical trap properties in polypropylene depend on the fine structure of the polymer.