The saturated temperatures of ethylphenyldimethoxysilane (EPDMOS) and ethylphenyldiethoxysilane (EPDEOS) were determined using an inclined ebulliometer from 2.035 to 64.0 kPa. The experimental data were fitted with the Antoine and Clarke-Glew equations by a weighted least-squares regression method, which yielded Antoine parameters (A = 9.1280, B = 1590.18, C = -100.39 K and A = 9.1049, B = 1678.64, C = -102.84 K) and standard vaporization enthalpies (Delta H-g(l)m(0)(298.15 K) = 62.52 kJ center dot mol(-1) and Delta H-g(l)m(0)(298.15 K) = 65.19 kJ center dot mol(-1)) for EPDMOS and EPDEOS, respectively. The critical properties of EPDMOS and EPDEOS, such as critical temperature, pressure, and volume, were estimated by the group contribution method introduced by Nannoolal et al. The acentric factors of EPDMOS and EPDEOS were estimated from these critical parameters and the reduced saturated vapor pressures calculated from either the Clarke-Glew equation or the Antoine equation.