Several new co-poly(arylene ether sulfone)s have been prepared by the reaction of 4,4'-fluorodiphenyl sulfone (FDS) with different bisphenols namely 4,4'-isopropylidenediphenol (BPA), 4,4'-hexafluoroisopropylidenediphenol (6F-BPA), and N-phenyl-3,3-bis(4-hydroxyphenyl) phthalimidine(PA). The homo-poly(arylene ether sulfone) s are named as 1a, 2a, and 3a. The copolymers namely 2b, 2c, 2d and 3b, 3c, 3d have been prepared, respectively, on reaction of FDS with BPA or 6F-BPA using different molar ratios of PA such as 25, 50, and 75. The poly(aryl ether sulfone) s 1a containing PA unit in the main chain showed a very high glass transition temperature of 280 degrees C and an outstanding thermal stability up to 510 degrees C for 5% weight loss under synthetic air. Depending on the mole% of PA, the glass transition temperatures of the copolymers can be varied. The polymers were soluble in a wide range of organic solvents. Transparent thin films of these polymers exhibited tensile strengths upto 84 MPa and Young's modulus up to 3.16 GPa. The films of these polymers showed low water absorption of 0.24%. Copyright (C) 2009 John Wiley & Sons, Ltd.