4,4'-Bis(3,4-dicarboxyphenylthio)diphenyl sulfone dianhydride(4,4'-PTPSDA) and 4,4'-bis(2,3-dicarboxyphenylthio)diphenyl sulfone dianhydride(3,3'-PTPSDA) were synthesized from chlorophthalic anhydrides and bis(4-mercaptophenyl)sulfone. Their structures were determined via IR spectra, H-1 NMR and elemental analysis. A series of polyimides were prepared from isomeric PTPSDAs and aromatic diamines in 1-methyl-2-pyrrolidinone (NMP) via the conventional two-step method. Polyimides based on 4,4'-PTPSDA and 3.3'-PTPSDA have good solubility in polar aprotic solvents and phenols. The 5% weight-loss temperatures of isomeric polyimides were near 500 degrees C in N-2. DMTA and DSC analyses indicated that the glass-transition temperatures of polyimides front 3,3'-PTPSDA are higher than those of polyimides from 4,4'-PTPSDA. The wide-angle X-ray diffraction showed that all polyimides are amorphous. The polyimides from 3,3'PTPSDA showed higher permeability but lower permselectivity compared with those from 4.4'-PTPSDA. (c) 2005 Elsevier Ltd. All rights reserved.