Two-stage copolycondensations of isophthalic acid/terephthalic acid (50/50) and a bisphenol (BP) first and then a comonomer BP were carried at 80 and 120 degreesC. BPs were divided into two groups: those with polar substituents and those without polar substituents. The copolycondensation with any combination of BPs proceeded nearly equally well at 80 degreesC. However, the reaction at 120 degreesC was retarded differently by the groups of comonomers. For the preformed oligomers from BPs without polar substituents, the temperature did not affect the reaction very much, but the reaction was significantly retarded with BPs containing polar groups. All of the reactions of the oligomers from BPs having polar groups with comonomer BPs, regardless of their substituents, were greatly disturbed by the temperature rising. The results were attributed to the temperature effect on the way in which the oligomers reacted with comonomers due to the interactions between them, and they were examined in terms of the distributions of comonomers determined by H-1 NMR.