The design and synthesis of a new unsymmetric monomer, 1-chloro-4-(4-fluorobenzenesulfonyl)naphthalene (1), was accomplished and polymerized with several bisphenols. Three of these polymers represent the successful incorporation of a bulky 1,4-naphthylene unit into the commercially known polysulfones, Udel, Radel R and Victrex. All unsymmetric polysulfones obtained were determined to be amorphous and displayed glass transition temperatures in the range of 218-288 degrees C. The gas permeability suffered while the permselectivity was marginally improved with naphthyl insertion into Udel.