A trifunctional, triamine 4-(4-aminophenoxy)-4 ',4 ''-diamino triphenylamine (A) was successfully synthesized byN-arylation in the presence of cesium fluoride, followed by catalytic reduction. A series of aromatic tree-shaped hyperbranched copolyimides (HBPIs, 1-4) was fruitfully synthesized by one-pot polycondensation of a newly synthesized triamine monomer (A), difunctional monomer 4,4 '-dianiline, 4,4 '-oxydianiline (ODA) and a series of aromatic dianhydride monomers. The appropriate molar ratio of triamine, ODA to the dianhydride monomer B is 1:1:2.5 for HBPIs synthesis using the A(2)A(3)B(5)type copolymerization approach. The synthesized HBPIs exhibited a moderate number-average molecular weight (25,700-28,400 g/mol) and polydispersity in the range 2.6-3.0 as revealed by gel permeation chromatography measurement. The oxidative thermal degradation analyses of the HBPIs showed that the synthesized materials are thermally stable up to 500 degrees C and glass transition temperature in the range 290-302 degrees C. The elongation at break was found in the range 4.8%-8.1% as revealed by tensile measurement. Besides, good thermal stability the HBPIs exhibited excellent flow, appreciable organosolubility, easy processability, and noticeable mechanical stability, thus suggesting their use as thermally resistant, protective coatings for various devices and outdoor environment in the future.