Polyamideimide was synthesized from rosin-maleic anhydride adduct by the reaction of its acid chloride with diaminodiphenyl-methane. The same polymer has also been prepared by the self-polycondensation of the amino acid prepared from the adduct and diaminodiphenylmethane in the presence of thionyl chloride at ambient temperature. The amino acid and the polymer were characterized by IR spectra and elemental analysis. The polymer was found to be soluble only in highly polar solvents. The inherent viscosity of the polymer was found to be low, indicating low molecular weight. The x-ray diffraction data indicated that the polymer was amorphous. The solubility parameter calculated from Small' group contribution agrees well with the experimental value. Ther-mogravimetric analysis, differential thermal analysis, and isothermal aging showed that the polymer was fairly thermostable.