A series of alternating polyamide-imides (PAIs) with fluorenyl cardo having inherent viscosities of 0.38-0.88 dL/g was synthesized by one-pot polycondensation of cardo diamines, trimellitic anhydride, and various aromatic diamines including p-phenylene diamine, m-phenylene diamine, 4,4 '-oxydianiline, 3,4 '-oxydianiline, 2,2-bis[4-(4-amino-phenoxy)phenyl]propane, 2,2-bis[4-(3-amino phenoxy)phenyl]propane using triphenyl phosphite as condensing agents. Most of the polymers were readily soluble in a variety of organic solvents, such as N-methyl-2-pyrrolidin-one, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, dimethyl sulfoxide, pyridine, and tetrahydrofuran, etc. PAIs exhibited better solubility when alkyl substituents were incorporated. Moreover, the effects of the linkage of imide/amide on the properties of PAIs were also discussed. The glass-transition temperatures of these polymers were recorded between 235 and 448 degrees C by DSC and 10% weight loss temperature of all polymers exceed 450 degrees C in air. The films of the resulting PAIs could be cast from their DMAc solutions. These films had a tensile strength in the range of 43-111 MPa, and an elongation at break in the range of 1.5-7.1%. (c) 2007 Wiley Periodicals.