Fundamental elementary facts and theoretical tools for the interpretation and model development of solid-gas interactions are first presented in this work. Chemical, physical and electrochemical aspects are presented from a phenomenological, thermodynamic and kinetic point of view. The theoretical aspects of electrical properties on the surface of a solid are also covered to provide greater accessibility for those with a physico-chemical background. The second part is devoted to the development of devices for gas detection in a system approach. Methods for experimental investigations concerning solid-gas interactions are first described. Results are then presented in order to support the contribution made by large metallic elements to the electronic processes associated with solid-gas interactions.