A new phthalimide-containing diamine N-[4-(4-aminophenyloxy)phenyl]-4-aminophthalimide was synthesized and polymerized with various aromatic tetracarboxylic acid dianhydrides via one-step polycondensation in p-chlorophenol to produce high molecular weight polyimides. In comparison with the polymers based on 4,4'-oxydianiline (ODA), the polymers prepared in this work had comparable or slightly higher solubility in spite of the presence of one more rigid phthalimide group in the repeat unit. They showed much higher glass transition temperatures (263-338 degrees C) and enhanced thermal stabilities observed from the temperatures (575-631 degrees C) at 5% weight loss. Some of the polymers exhibited crystalline transitions even though they have bent groups and non-symmetric chain structure leading to irregular repeating sequences.