An automatic adiabatic differential calorimeter has been constructed to record the release spectrum of stored energy of deformation of metals from −196 to 500°C. A cold worked and an annealed specimen contain internal heaters which are powered by amplifiers, the signal inputs to which are specimen‐to‐calorimeter wall differential thermocouples. Control circuits attempt to maintain conditions as adiabatic as possible, and the power difference to the specimen heaters necessary to do this is taken as the stored energy of deformation.