A new method is described for measuring the tensile strength of weak powder compacts by applying stress to a vertical powder test piece, formed and supported by the glass and metal surfaces of a split cell. Tension is applied by slowly stretching a long vertical spring to which the upper powder support is attached, until brittle fracture occurs at the unsupported waist of the test piece. Tensile strength is calculated from the spring elongation at fracture. The instrument is designed to measure tensile strengths in the range 10-2000 N m-2 at temperatures up to 200 degrees C. There are two modes of operation for separate or joint determination of shear and tensile properties. The ability to function in the presence of high electric fields (up to 2 kV mm-1) is an additional feature of the equipment.