AbstractTetrachlorodiphenyl cyclotriphosphazene N3P3Cl4(C6H5)2(TPC) has been synthesized by Friedel‐Crafts reaction. The polycondensation of TPC with aromatic diamine compounds has been carried out in pyridine. The products obtained from the reaction of TPC with aromatic diamine compounds were slightly soluble in polar organic solvents. The molecular weights measured by the method of end group analysis were about 2800 to 10800. The products were amorphous, brown, yellow or white coloured solids. The softening points of all polycondensation products were found to be in the region of 100°C to 120°C. The electrical conductivity of the products obtained from TPC with p‐phenylenediamine and p,p′‐diaminodiphenyl sulfone was determined to 5 × 1012(Ωcm)−1and 1 × 1015(Ωcm)