The degradation of (110) surface as a working surface in the -based sensor is studied. Theoretical and experimental investigations of electronic and atomic processes on this surface caused by the adsorption of molecules are performed. In the framework of the density functional theory, we determined the energetically preferable position of the adsorbed molecule over surface. It was found that the adsorbed molecule is mainly “bonded” with In atom. The redistribution of the electron density around In atom leads to a weakening of chemical bonds in the vicinity of In atom, and this circumstance is a reason of its destabilization. The temperature dependence of the resistance of films in a wide interval of temperatures was measured. This dependence is characterized by a specific maximum. The obtained experimental results are interpreted using theoretical results concerning a destabilization of surface In atoms induced by the adsorbed molecules and, on the basis of our recent results in an earlier paper, concerning a high-temperature degradation of the (110) surface layers as a working surface in sensor devices. We suggested a two-stage model of the degradation process: In the first stage, the disordering of surface caused by -adsorption-stimulated displacement of In atoms leads to the increase of surface resistance, and in the second stage, displaced In atoms form precipitates and this process causes a metallization of surface and a decrease of the resistance.