A new bifluoro-monomer containing naphthalene, 1,4-bis(4,4'-fluorobenzoyl)naphthalene was successfully synthesized via a two-step procedure. Four poly(aryl ether ketone)s containing naphthalene were prepared from 1,4-bis(4,4'-fluorobenzoyl)naphthalene via the nucleophilic aromatic substitution polycondensation with four bisphenol monomer containing fluorine or not containing fluorine. Because of the incorporation of naphthalene, the resulting poly(aryl ether ketone)s exhibited outstanding thermal stability. The glass transition temperatures are above 170 degrees C, and the temperatures at a 5% weight loss are above 460 degrees C in air. All these polymers are amorphous and soluble in common organic solvents. These polymers can form strong, transparent, and flexible films with strengths of 105-119 MPa, Young's moduli of 2.05-2.31, and elongations at break of 14-29%. The dielectric constants estimated from the refractive indices of the poly(aryl ether ketone) films are 2.82-2.96. (c) 2006 Elsevier B.V. All rights reserved.