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(CH3NH3)5Bi2Br11 (MAPBB) crystals exhibits ferroelectrics phase transitions at 311 K and additional anomaly of physical properties at 77 K. The results of temperature study of the specific heat for the (CH3NH3)5Bi2Br11 crystals are presented at temperature range of 6-277 K. The characteristic anomaly of temperature dependence of specific heat was observed at 72.4 K. It was established, that description of the experimental Cυ(T) dependence at temperatures below anomaly can be achieved with two Debye functions (ΘD(1) = 47 K and ΘD(2) = 215 K) and one low-frequency Einstein-type term (ΘE = 73 K). In order to fit Cυ in the temperature range above the anomaly another Einstein-like term with ΘE = 233 K must be included with double number of modes. The entropy AS connected with the low temperature anomaly reaches the magnitude of 2Rln2. [ABSTRACT FROM AUTHOR]