Low-dielectric-constant SiOC(-H) films were deposited on p-type Si (100) substrates by using plasma-enhanced chemical- vapor deposition with methyltriethoxysilane and oxygen gas as precursors. SiOC(-H) films are prepared with different radio frequency (rf) powers and annealed at different temperatures in an Ar ambient for 30 min. The film thickness and the refractive index were measured by using field emission scanning electron microscopy and ellipsometry, respectively. The bonding characteristics and the relative concentrations of the bonds in the films were investigated by using Fourier transform infrared spectroscopy in the absorbance mode. The dielectric constant of the SiOC(-H) film was evaluated by using C-V measurements on the metal-insulator-semiconductor, Al/SiOC(-H)/p-Si structure, and the experimental lowest dielectric constant of the SiOC(-H) film was found to be 2.28 at an annealing temperature 500 °C. These results reveal the promising characteristics of SiOC(-H) films deposited by using methyltriethoxysilane and oxygen gases.