The low-temperature heat capacity of 2-thiopheneacetic acid was measured in the temperature range from 78 to 343 K with a high precision automated adiabatic calorimeter. No phase transition or other thermal anomaly was observed in the temperature ranges of 78～314 and 337～343 K, in which the molar heat capacities were fitted to two polynomials by means of the least square fitting. A solid-liquid phase transition was observed in the temperature range of 314～337 K. The melting point, molar enthalpy and entropy of fusion, and molar purity of this compound were determined to be 335.745 K, 16.260 kJ•mol^－1, 48.415 J•K^－1•mol^－1 and 98.56%, respectively. The thermodynamic functions of 2-thiopheneacetic acid relative to the reference temperature 298.15 K were derived based on the heat capacity data in the temperature range of 80～340 K.

Key words: 2-thiopheneacetic acid, adiabatic calorimetry, heat capacity, thermodynamic function