The performance of ultra-thin Au-Ag-Au tri-layer film deposited thermally over a flexible substrate is investigated using structural, optical, mechanical and electrical-transport measurements. The optimum total thickness of the tri-layer for high transparency and conductivity is determined to be around 8 nm using a theoretical model. The Au-Ag-Au tri-layer shows maximum transmittance (congruent to 62%) at wavelength 500 nm. XRD pattern shows peak corresponding to (111) plane of Au and/or Ag. Sheet resistance (congruent to 10.42 Omega/square) measured at 300 K using four probe technique is stable up to 150 degrees C. Hall effect measurements show high conductivity (1.34 x 10(5) (Omega cm)(-1)), carrier concentration (2.48 x 10(23)/cm(3)), and mobility (3.4 cm(2)/Vs). Scotch tape test confirms good adhesion of the film onto PET substrate. Bending-twisting tests using an indigenous apparatus indicate high resistance-stability even after 50,000 cycles. These results imply the viability of Au-Ag-Au tri-layer film as a transparent conducting electrode worth exploring for optoelectronic applications.