New polyimides (Pis) containing thioether and sulfonyl groups in their main chains have been developed. These Pis were synthesized by a two-step polycondensation procedure from several dianhydrides Such as 4,4'-[p-thiobis(phenylenesulfanyl)] diphthalic anhydride (3SDEA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4'-[sulfonylbis(phenylenesulfanyl)] diphthalic anhydride (pDPSDA) and a new sulfonyl and sulfur-containing aromatic diamine, 2,7-bis(4'-aminophenylenesulfanyl)thianthrene-5,5,10,10-tetraoxide (APTTT). All of the Pis show good thermal and optical properties such as optical transparency higher than 80% at 450 nm for a thickness of ca. 10 mu m, glass transition temperatures higher than 250 degrees C, thermal decomposition temperatures (T-10%) in the range of 504-514 degrees C. Because of the two sulfonyl groups at each monomer unit in the polymer main chain, all of the Pls show good transparency maintaining relatively high refractive index. (C) 2008 Published by Elsevier Ltd.