A method of directly measuring the temperature rise during high speed torsion tests is described. The test sample is formed by welding two materials of similar mechanical properties but different thermoelectric characteristics and ensuring, by reducing the section, that the gauge length includes the thermocouple junction. A number of tests were conducted using the nickel base thermocouple alloys Nicrosil and Nisil (I.S.A. Type N). The temperature rise observed during uniform deformation agrees with that expected from simple thermomechanical calculations. Void growth and coalescence lead to a strain concentration and ductile fracture which is accompanied by a more significant temperature rise.