Abstract: A method of controlling the temperature of a probe in materials testing apparatus, and apparatus operating by that method are disclosed. The apparatus includes heating elements that can by supplied with energy to apply heat to the probe. The method has a heating phase. In the heating phase, closed-loop temperature control is used to supply energy to the heating elements to heat the probe to a target temperature. When the probe has reached the target temperature, the average power that is being supplied to the heating elements is determined. Then, in a temperature maintenance phase, a continuous constant source of energy at a power that is substantially equal to the determined average power is supplied to the heating elements to maintain the probe at the target temperature.