The elastic and thermal properties of 4,4’-(hexafluoroisopropylidene)-bis (phthalic anhydride)-4,4’-bis(4-aminophenoxy) biphenyl (6FDA-APBP) free-standing polyimide films (2-10 mu m) were investigated using impulsive stimulated thermal scattering (ISTS), a non-contact optical method for thin film characterization. Shear and longitudinal velocities, Young’s modulus, Poisson’s ratio and the in-plane thermal diffusivity are reported.