Low dielectric constant SiOC(-H) films were deposited on p-type Si (100) substrates by plasma enhanced chemical vapor deposition (PECVD) using methyltriethoxysilane (MTES; C7H18O3Si) and oxygen gas as precursors. The SiOC(-H) films were deposited at room temperature and then annealed. Nanoindentation studies were carried out in order to determine the mechanical properties of the SiOC(-H) films. The elastic modulus and hardness of SiOC(-H) films were measured to be in the range of 2.14 - 5.02 and 0.12 - 0.74 GPa, respectively. It was observed that the values of elastic modulus and hardness decreases with increase of flow rate ratio of the precursors. In the SiOC(-H) film, -CH3 group as an end group was introduced into -O-Si-O- chain network, thereby reducing the film density to decrease the values of the mechanical properties.