In this paper are described an irradiation calorimeter and data acquisition system used for simultaneous determinations of the rates of energy release and of resistivity recovery during anneals at low temperatures of irradiated metals. Both rates are measured on the same sample. the system provides efficient heat transfer from the specimen during irradiations and a good, reproducible degree of thermal isolation of the specimen during anneals. Necessary corrections to the raw data are discussed. The application of these measurements to determination of the energy released by interactions which immobilize self‐interstitial atoms is described and illustrated by data from the recovery between 12 and 35 K of platinum irradiated with 20.6‐MeV deuterons.