The heat capacity of crystalline bis(4-chlorophenyl)sulfone was measured from the temperature T = 14 to T = 300 K by adiabatic calorimetry. An incommensurate phase transition was detected as a second-order type of heat-capacity anomaly at T = (148.5 +/- 0.5) K. The molar enthalpy and the molar entropy of transition were (43.1 +/- 0.1) J.mol-1 and (0.314 +/- 0.005) J.K-1.mol-1, respectively. Some thermodynamic functions were calculated from the heat-capacity results and the values were tabulated.