A cryostat has been constructed and is described which permits the tensile deformation of metal specimens under loads up to 150 kg and simultaneous measurements of the thermal and electrical conductivity, thermal diffusivity, and heat of deformation, preferably at temperatures of liquid helium. The apparatus is designed to keep liquid helium for approximately 20 h, which permits the investigation of occurrences requiring high resolution in time, as for example the discontinuous slip at low temperatures. The measurement of the temperature and small temperature differences is achieved through the application of gas thermometers in connection with electronic differential pressure sensors of small dead volume. Automatic recording allows for an accurate observation of thermal transients. The thermal conductivity measurements are based on the Kohlrausch method. Some results which are representative for the application of the apparatus are presented.