The purpose and design of a novel high-temperature triaxial-torsional testing machine for concrete and rock is described. The temperature range is up to 600 ¿C, the maximum axial load is 5 MN, the maximum confining pressure is 140 MPa and the maximum torque is 5555 NM. The testing chamber is cylindrical with a diameter 241 mm and length 686 mm. The machine will be used for testing concrete under conditions of nuclear reactor accidents, as well as for the development of general constitutive relations for solid or cracked concrete and rock.