The synthesis and characterization of novel thermotropic liquid crystalline poly(aryl ether ketone)s based on the reaction of a liquid crystalline mesogen containing monomer, biphenol, and a crystal-disrupting substituted monomer, t-butyl- or phenyl-, hydroquinone with 4,4’-difluorobenzophenone are described. Two families of copolymers-a biphenol/t-butylhydroquinone series of 90, 75, 50, 25, and 0% biphenol, and a biphenol/phenylhydroquinone series of 75, 50, 25, and 0%-are evaluated. Thermotropic liquid crystalline behavior was observed in the copolymers containing 50 and 75% biphenol. The first order and second order transitions associated with melting, crystallization, thermotropic liquid crystalline mesophases, and glass transition temperatures (Tgs) of each copolymer are investigated. The thermal transitions are correlated with optical microscopy and X-ray and/or electron diffraction characteristics. It was observed that the Tg increases and end group concentration decreased after isothermal heat treatment indicative of further polymerization. These materials are believed to be the first known thermotropic liquid crystalline poly(aryl ether ketone)s.