A new cardo diimide-dicarboxylic acid, 1,1-bis[4-(4-trimellitimidophenoxy)phenyl] cyclododecane (BTPCD), containing a pendant cyclododecyl group was synthesized by the condensation reaction of 1,1-bis[4-(4-aminophenoxy)phenyl] cyclododecane with trimellitic anhydride in glacial acetic acid. A series of new cardo polyamide-imides were prepared by the direct polycondensation of BTPCD and various aromatic diamines in N-methyl-2-pyrrolidinone (NMP) with triphenyl phosphite and pyridine as condensing agents. The polymers were produced in high yields and with moderate-to-high inherent viscosities of 0.72-1.02 dL g(-1). The number-average and weight-average molecular weights of the polymers ranged from 21,000 to 49,000 and 58,000 to 92,000, respectively. All the polymers exhibited excellent solubility and could be readily dis solved in various solvents such as NMP, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, pyridine, cyclohexanone, and tetrahydrofuran. These polyamide-imides had glass-transition temperatures between 241 and 262 degrees C and 10% weight-loss temperatures ranging from 469 to 511 degrees C in nitrogen. The polymer films had a tensile strength range of 79-108 MPa, an elongation at break, range of 7-14%, and a tensile modulus range of 2.0-2.4 GPa.