Abstract: The optical characteristics of silicon oxide thin films deposited by the reactive magnetron (RMS) method were compared to those deposited by the reactive ion-beam sputtering (RIBS) method. Dependence of refractive index n, extinction coefficient k and deposition rate on oxygen concentration in Ar/O2 working gas mixture were determined. Silicon oxide films with the refractive index of 1.52～1.55 and extinction coefficient less 10-5 at the wavelength of 0.63m were deposited by RMS method with O2 content greater than 15% of working gas mixture. Silicon oxide films with refractive index of 1.52～1.6 and extinction coefficient less 10-5 were deposited by RIBS method with O2 content more than 80% of working gas mixture. In the case of RMS method, the SiO2 film deposition rate decreases almost 5 times when the process is switched to the reactive mode (more than 15% O2). On the contrary, in the case of RIBS, the deposition rate does not depend on the O2 concentration in the working gas mixture.