Two new bisphenol monomers containing naphthylene groups were synthesized by a Friedel-Crafts acylation reaction followed by a demethylation reaction. Four naphthylated poly( aryl ether ketone)s (PANEKs) were successfully prepared via a typical nucleophilic substitution polycondensation. These PANEKs exhibited excellent properties including high T(g)s (above 204 degrees C) and good thermal stability ( the temperature at 5% weight loss in air was above 430 degrees C). They had improved solubility, and flexible and transparent membranes could be cast from their solutions. The good mechanical property ( tensile strength of 82.2 similar to 102.8 MPa, Young's moduli of 2.1 similar to 2.4 GPa, and elongation at break of 17 similar to 31%) indicated they were strong materials. Low dielectric constant (2.8-2.9 at 1 MHz) and moisture absorptions (similar to 0.45%) were also detected from the polymer films.