Commercially available polyethylene terephthalate (PET) film of thickness of 20 μm has been used as flexible substrate and aluminum has been coated on PET film using vacuum thermal evaporation method. The structural characterization of Al-PET film has been done using X-ray diffraction (XRD) pattern and Fourier transform infrared (FTIR) spectroscopy. Mechanical study of Al-PET film has been carried out using Dynamic Mechanical Analyzer (DMA). The glass transition temperature (Tg) of Al-PET film is found to be 112.3°C whereas Tg of commercial PET film is 89.7°C. The result of stress-strain behavior of polymer films for a wide range of temperatures is useful for engineering applications therefore in the present work an effort has been made to see the effect of wide range of temperatures on metalized polymer. The stress-strain curves of Al-PET film at room and elevated temperatures explain the mechanical response of this film under the applied load.