Аннотация:An experimental investigation was made of the temperature dependences of the specific heat of pure triglycine sulfate single crystals as well as of crystals containing chromium and alpha -alanine impurities. The investigation was carried out in the range 20-70 degree C. The measurements were made by a dynamic method described in the paper. It was found that the specific heat discontinuity broadened when impurities were introduced; moreover, the temperature dependence of the specific heat of pure crystals depended on whether the temperature was rising or falling. These effects were attributed to the locking of the spontaneous polarization at the points where defects and impurities were located, which resulted in an inhomogeneous transition of a crystal through the phase transition point.