This paper describes an adiabatic aneroid calorimeter for the measurement of the specific heat of high polymers over the temperature range −20 to 300°C.The temperature of its adiabatic jacket can be automatically recorded and, for the most part, automatically controlled, thus making possible the convenient study of temperature drifts, heat exchanges, and methods of correcting for such errors. Duplicate experiments have been carried out within an average deviation of 0.5 to 0.6 percent error, but the absolute error may be between one or two percent.