Abstract: A low-temperature process for producing the GaAs MIS structure based on the slow evaporation of powder SiO on the room-temperature GaAs substrate is developed. The as-grown GaAs-SiO MIS has a low interface state density of 8×10¹¹/cm²·eV and a low hysteresis. No frequency dispersion of the accumulation capacitance is found, as explained by the frequency-dependent permittivity of SiO.