Thermal stability of a recently synthesized polymeric methyl-di(phenylethynyl)silane (MDPES) resin was studied using a number of thermal and spectrometric analytical techniques. The polymer exhibits extremely high thermal stability. Thermogravimetric analysis (TGA) shows that the temperature of 5% weight loss (T-d5) was 615 degrees C and total weight loss at 800 degrees C was 8.9%, in nitrogen atmosphere, while in air, Td5 was found to be 562 degrees C, and total weight loss at 800 degrees C was found to be 55.8% of the initial weight. Differential thermal degradation (DTG) studies show that the thermal degradation of MDPES resin was single-stage in air and two-stage in nitrogen. The thermal degradation kinetics was studied using dynamic TGA, and the apparent activation energies were estimated to be 120.5 and 114.8 kJ/mol in air, respectively, by Kissinger and Coats-Redfern method. The white flaky pyrolysis residue was identified to be silicon dioxide by FTIR and EDS, indicating that the thermal stability of polymer may be enhanced by the formation of a thin silicon dioxide film on the material surface. (c) 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:605-610,2007