Poly(arylene ether 1,3,4-oxadiazoles) were prepared, containing C(CH3)(2), C(CF3)(2), and SO2 groups that show good solubility in dimethylacetamide and sulfuric acid. The solubility was higher for copolymers containing two of these groups above. All of the polymers and copolymers were sulfonated. While sulfonation using CISO3Si(CH3)(3) did not take place even after days of reaction, sulfonation with sulfuric acid was complete after 1.5 h. The degree of sulfonation varied from 1.0 to 4.0 sulfonate groups per repeat unit. Sulfonated homopolymers with C(CF3)(2) groups were insoluble in water even with a sulfonation degree of 2.0. The polymers were further characterized by NMR, elemental analysis, differential scanning calorimetry and thermogravimetry. (C) 2004 Elsevier B.V. All rights reserved.