A thermoanalytical instrument, and especially a differential scanning calorimeter, has first and second measurement positions, a heater and a temperature sensor associated with each of the measurement positions, and a controller. The controller, which has an associated means for setting a predetermined temperature program, controls a heating power of the first heater to cause the temperature measured at the first position to follow the temperature program. The controller also controls both heaters to eliminate any temperature difference between the measured first and second temperatures. The controller also provides a means for determining the lower of the measured first and second measured temperatures and applies additional power to the heater associated with that lower measured temperature.