A novel, fluorinated diamine monomer with the ether-ketone group, 4,4'bis(4-amino-2-trifluoromethylphenoxy)benzophenone (2), was prepared through the nucleophilic substitution reaction of 2-chloro-5-nitrobenzotrifluoride and 4,4'-dihydroxybenzophenone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Flourinated polyimides (PIs) 5a-f and copolyimides (co-PIs) 5c/a-f were synthesized from 2 and various commercial aromatic dianhydrides via thermal or chemical imidization. PIs 5a-f had inherent viscosities ranging from 0.72 to 1.22 dL/g. Besides the chemical imidization of 5c(C), the 5(Q series were soluble in amide-type solvents and even in less polar solvents, but PIs 5a-f prepared via thermal imidization were insoluble. PI films 5a-f exhibited tensile strengths ranging from 92 to 112 MPa, elongations at break from 8 to 15%, and initial moduli from 2.0 to 2.1 GPa. The glass-transition temperatures of the 5 series were in the range of 232-278 degreesC, and the 10% weight-loss temperatures were above 535 degreesC, with more than a 50% char yield at 800 degreesC in nitrogen. In comparison of the PI 5 series with the analogous non-fluorinated PIS 6 series based on 4,4'-bis(4-aminophenoxy)benzophenone, the 5 series revealed better solubility, lower color intensity, dielectric constant, and moisture absorption. Their PI films had cutoff wavelengths between 370 and 410 mn, V values ranging from 9.6 to 58.3, dielectric constants of 3.05-3.64 (1 MHz), with moisture absorption in the range of 0.08-0.38 wt %. (D 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 222-236, 2004.