In this letter the observation by scanning tunneling microscopy of a Au(111) surface reconstruction induced by prolonged annealing of gold films in oxygen (pO2=1 bar) at high temperature (T=800 °C) is reported. At the atomic scale, the surface is characterized by a (&sqrt;3×&sqrt;3)R30° surface structure. In addition, the surface exhibits a long‐range ordered hexagonal superstructure with a periodicity of 80 A˚ and a corrugation of about 0.5 A˚. Convincing evidence is presented that this surface morphology is induced by chemisorption of atomic oxgyen at the Au(111) surface. ©1995 American Institute of Physics.