This work reports the synthesis of new diamantane-based polyimides by the reaction of 4,9-diaminodiamantane (I) with various aromatic tetracarboxylic dianhydrides. The polyimide film IVa has a low dielectric constant of 2.7 and a low moisture absorption of 0.205%. The number-average molecular weight ((M) over bar(n)) of polyimide IVa is 37 kg/mol. Dynamic mechanical analysis (DMA) reveals that polyimide IVa has only a glass transition at 308 degrees C on the temperature scale between 0 and 350 degrees C. The glass transition temperatures of the polyimides were also found to be 295-325 degrees C by means of a differential scanning calorimetry (d.s.c.). The polyimide IVa had tensile strength at breakage of 68.4 MPa and initial modulus of 2.0 GPa. The temperatures of polyimides at a 5% weight loss ranged from 432 to 488 degrees C in air and from 489 to 530 degrees C in N-2 atmosphere. The polyimide IVa is soluble m-cresol.