Abstract: A method for testing a fuel rod cladding tube enables an operation-oriented assessment of its corrosion behavior. The fuel rod cladding tube is partly immersed in a surrounding medium and heated from inside. An electrode potential of the fuel rod cladding tube is measured relative to a reference electrode and measured data are used to extrapolate material characteristics of the fuel rod cladding tube, in particular its corrosion characteristics. A device for carrying out the method includes a pressure vessel to be filled with a surrounding medium and having an aperture opening in a vessel wall for insertion of the fuel rod cladding tube into the pressure vessel through the aperture opening. A heating apparatus is disposed in the interior of the fuel rod cladding tube and an electrically insulating sealing body is disposed between the fuel rod cladding tube and the vessel wall.