A gas analyzer having an analysis or sensor unit and having an electronic processing unit, and a method for operating such a gas analyzer. In order to achieve substantially improved safety both in handling corrosive and/or combustible and/or toxic gases in a not potentially explosive atmosphere (ex-free atmosphere), and in the operation of such an analyzer in an exatmosphere, the analysis or sensor unit as such is of non-explosive configuration and is arranged in a gas tight chamber through which a toxic and/or corrosive and/or combustible gas flows and around which a second chamber is arranged.