Two series of polyimides based on laterally attached p-terphenyl and biphenyl groups were synthesized. The solubility and thermal properties were studied using DSC, thermogravimetric analysis, and the solubility test. These polymers exhibited good thermal stability and excellent solubility. The high solubility for both polymer series was attributed to the non-coplanarity of diamine monomers and the use of fluorinated dianhydride, whereas the slightly better solubility for polymers based on p-terphenyl was attributed to further weakening of interchain interaction of the polymers. Both polymer series exhibited glass-transition temperatures (Tg's) in the range of 244-272 degreesC. The T-g's of polymers containing laterally attached p-terphenyls were higher than those of their counterparts containing biphenyls by 5-17 degreesC. This was attributed to the formation of an interdigitated structure that hinders the segmental movement of polymer chains.