We previously reported the synthesis of pentaethoxydisiloxane (PEDS) by the oxidation of triethoxysilane (TES) with oxygen gas in the presence of a Rh catalyst. However, the isolate yield of PEDS was low (< 7%). Herein, we report a PEDS yield of 62% using a new synthetic method and the characterization of the PEDS polymer by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. The PEDS polymer was synthesized by hydrolysis-condensation of PEDS, and this polymer was composed of linear and branched chains and was the end group of the Q¹ unit.