Polyimides with a combination of proper-ties including low solar absorptivity (a) in thin films, atomic oxygen (AO), and ultraviolet (UV) radiation resistance, solubility in organic solvents in the imide form, high glass transition (T-g) temperatures, and high thermal stability have been prepared and characterized. The polymers were prepared by reacting a novel aromatic diamine, [2,4-bis(3-aminophenoxy)phenyl)diphenylphosphine oxide (2), with aromatic dianhydrides in a polar aprotic solvent. The diamine was prepared from commercially available starting materials in a two-step reaction in relatively high yield. Copoly(amide acid)s and copolyimides were prepared using 2 in combination with other commercially available aromatic diamines. The chemistry as well as physical and mechanical properties of the polymers and films will be discussed.