Dry oxygen pressure at 500 atm is used to grow SiO2 films 103 nm thick on silicon at 80°C. The residual film stress, chemical etch rate, refractive index, and density of the pressure-oxide films is measured and compared with measurements of thermal oxide films prepared at 1 atm dry oxygen pressure. The high pressure/low temperature films exhibited higher refractive indexes, slower chemical etch rates, and higher measured densities compared to 1 atm thermal oxides prepared at 1000°C. These results are attributed to the lower oxidation temperature rather than the higher oxidation pressure of the pressure-oxide films. It is concluded that the formation of higher density SiO2 films is a specific result of low temperature processing. The use of high pressure oxidation provides a convenient technique to prepare the low temperature high density SiO2 films of sufficient thickness for further study. © 1980, The Electrochemical Society, Inc. All rights reserved.