The molar heat capacity values of the binary system composed of 0.716 molar fraction H2O+0.284 molar fraction n-C4H9OH were measured by an adiabatic calorimeter in the temperature range from 78 K to 320 K.The functional relationships of heat capacity with respect to thermodynamic temperature were established.Glass-transition occurred at(111.9±1.2)K.The phase transitions took place at (179.26±0.77)K and (269.69±0.14)K corresponding to the solid-liquid phase transitions of n-butanol and water

respectively. The phase-transition enthalpy and entropy of water were calculated. The thermodynamic functions of the binary systems relative to 298.15 K were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.