A new type of radiometer is described that is suitable for the measurement of the intensity of thermal radiation in the range of 1–100 cal/cm2 sec. The instrument is a simple one. It produces an emf directly proportional to intensity and can be made to have a time‐constant of the order of 0.001 sec. Equations are derived to predict the performance of the instrument, and their results are compared with experimental data obtained from three prototypes.