The modification of polyimide films by tin-complex incorporation has been studied with the aim of producing materials with the mechanical and thermal properties of polyimide with enhanced electrical properties. A variety of Sn(II) and Sn(IV) complexes have been incorporated into BTDA/ODA (3,3 14,4 1-benzophenonetetracarboxylic acid dianhydride / 4,41- oxydianiline) and PMDA/ODA (pyromellitic dianhydride/4,4 1 -oxydianiline) derived polyimides in a 1:4 (complex/polymer repeat unit) molar ratio. Tin-complex incorporation was seen to have a variety of effects upon polyimide properties, depending upon the particular tin-complex employed. All films produced were thermally stable with decomposition temperatures> 500°C. Most films were homogeneous and flexible. / Master of Science