We have performed density-functional theory calculations of the atomic structure and the oxygen adsorption properties of Au(110) surfaces. The relaxations of missing-row reconstructed Au(110)-(1×2) surface are calculated to be -15.0%(Δd12/d0) and -1.1%(Δd23/d0). The relevant surface energy and workfunction are calculated to be 52.7 meV/2 and 5.00 eV, respectively. In the case of missing-row reconstructed Au(110)-(1×3) surface the surface atomic relaxations are calculated to be -20.5 %(Δd12/d0) and +2.7 %(Δd23/d0) which are quite differente from those of Au(110)-(1×2). However, in the later case, the surface energy and workfunction are found to be very close to those of missing-row reconstructed Au(110)-(1×2) surface, i.e., 53.4 meV/2 and 4.98 eV. We have simulated the scanning tunneling microscope (STM) images of both reconstructed surfaces and found that the missing row exhibits a remarkable hollow in the STM morphology. The further calculation of oxygen adsorption on both surfaces reveals that the adsorption energies in these cases are negative. These results indicate that the Au(110) surface is free from oxygen adsorption and reaction, showing highly chemical inertia.