Apparatus for the measurement of thermoluminescence is described which generates glow curves with an overall reproducibility of ±5per thousand. Particular attention has been given to the design of a controller capable of accurately reproducing a chosen linear heating rate (0.1-99.9°Cs-1) up to a predetermined final temperature (ambient to 990°C). A manually operated 'hold' facility for intermediate temperatures is also provided. The construction of the light-measuring system and checks on its stability, sensitivty and linear response to very weak sources are also described.