The approach of utilizing combustion synthesis to make fine particles of SiO_2, A1_2O_3 and TiO_2 is a quite modern technology. Through the chemical reaction in post-flame region, fine SiO_2 particles can be formed with high purity on plate surface. Therefore, the combustion synthesis of SiO_2 powders is an important area for further research and development especially for the application of SiO_2 in the semiconductor industry. This investigation proposes an experimental approach (i.e., a gas-phase combustion synthesis) using two different kinds of organic compounds, Hexamethyldisilazane (HMDSA) and Hexamethyldisioxane (HMDSO), as the silicon precursors. A premixed gas burner is chosen with C_3H_8 as fuel air as oxidant and part of the air was used as the carrying gas to entrain HMDSA/HMDSO vapor into the combustible mixture. Observations show that the C3H8/air flame changed color from a pale-blue flame to light yellow and then orange when different amounts of precursors were introduced. Through the chemical reaction in the post-flame region, fine SiO2 particles were formed in the gas phase and then quenched and collectal on an aluminum flat plate. The objective of this paper is to study the effects of HMDSO and HMDSA concentrations and flame temperatures on the synthesis of SiO2 particles. The approach of utilizing combustion synthesis to make fine particles of SiO 2, A1_2O_3 and TiO_2 is a quite modern technology. Through the chemical reaction in post-flame region, fine SiO_2 particles can be formed with high purity on plate surface. of SiO 2 in the semiconductor industry. This investigation proposes an experimental approach (ie, a gas-phase combustion synthesis) using two different kinds of organic compounds, Hexamethyldisilazane (HMDSA ) and Hexamethyldisioxane (HMDSO), as the silicon precursors. A premixed gas burner is chosen with C_3H_8 as fuel air as oxidant and part of the air was used as the carrying gas to entrain HMDSA / HMDSO vapor into combustible mixture. Observations show that the C3H8 / air flame changed color from a pale-blue flame to light yellow and then orange when different amounts of precursors were introdu ced. Through the chemical reaction in the post-flame region, fine SiO2 particles were formed in the gas phase and then quenched and collectal on an aluminum flat plate. The objective of this paper is to study the effects of HMDSO and HMDSA concentrations and flame temperatures on the synthesis of SiO2 particles.