Positron backscattering was observed at interfaces of polymer/metal using positron annihilation lifetime spectroscopy in the Teflon and Mylar films and poly (MMA‐co‐nBMA) acrylic coatings on tungsten (W) and molybdenum (Mo) substrates. Aluminum (Al) used as a comparison substrate did not have significant backscattering. Major changes were observed in the third,I3, and fourth,I4, intensity components of thin layers of Teflon and Mylar films on W and Mo substrates compared to Al. The average value of positron backscattering was estimated at 39% and 32% for W and Mo, respectively, with a22Na source. A model was presented for calculation of the backscattering coefficient (B) in the polymer/metal systems and compared with experimental results. ©1996 American Institute of Physics.