A series of novel polyimides have been synthesized from the condensation of 5-(perfluorononenyloxy)isophthalic acid bis(4-aminophenyl) ester (IV3) with various aromatic tetracarboxylic dianhydrides. For comparison, the polyimides containing the bis(4-aminophenyl) ester unit were prepared from terephthalic acid bis(4-aminophenyl) ester (IV1) and isophthalic acid bis(4-aminophenyl) ester (IV2) with dianhydrides. The poly(amic acid)s had inherent viscosities of 0.97-1.98 dl g(-1), depending on the diamines and dianhydrides. Perfluorononenyloxy group-containing polyimides (VII3a-d) had lower dielectric constant (ranged from 2.73 to 2.56), lower moisture absorption, and better solubility than those of analogous polyimides (VII1a-d, VII2a-d) which do not contain perfluorononenyloxy group. Moreover, they maintained good mechanical properties (G＇ close to 10(9) Pa) up to 270 degrees C. The glass transition temperatures of these perfluorononenyloxy groups containing polyimides were in the range of 268-287 degrees C by d.s.c. and 272-291 degrees C by d.m.a., and the 10% weight loss temperatures in nitrogen and air were above 529 and 522 degrees C, respectively.