Carborane-incorporated poly(silyleneethynylenephenyleneethynylene)s with different side groups were synthesized from corresponding poly(silyleneethynylenephenyleneethynylene)s and decaborane (B10H14) in the presence of acetonitrile through in-situ reaction. The obtained polymers with o-carborane units were characterized by using Fourier transform infrared and nuclear magnetic resonance spectroscopies, rheological measurements, differential scanning calorimetry, and thermogravimetric analysis. The results show that the properties of these carborane-incorporated polymers vary with side groups in main chains. They possess good processability and can be crosslinked to form thermosets at temperatures less than 250 degrees C. The thermosets exhibit excellent thermal and thermooxidative stabilities. The weight losses of the thermosets heated to 800 degrees C in air are only 10% approximately. After pyrolysis of the thermosets in nitrogen at 1000 degrees C, the pyrolytic products have no further weight losses up to 1000 degrees C in air. POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers