A new process for plasma oxidation of GaAs has been developed. Oxide films formed by this simple one‐step dry process have amorphous structure, with composition and thickness uniformity better than ±10% over areas ≲1 cm2. They have a gallium‐to‐arsenic ratio of nearly one. The electrical properties (I‐V,C‐V) of the films are such that this process may be useful in device fabrication.