The molar heat capacity of borazane BH3-NH3 was determined in the 10-289 K range. Two different adiabatic calorimeter systems, each using the classical heat-step method, were applied for the measurements. The molar standard entropy of borazane at T=298.15 K was determined to be S-0=96.34 J K-1 mol(-1). For the phase transition at T=224 K, a transition entropy of Delta S=6.87 J K-1 mol(-1) was calculated from the heat capacity data. The results of X-ray powder diffraction confirm an order-disorder transition with a change of the lattice structure from orthorhombic to tetragonal. From low-temperature differential scanning calorimetry, a transition enthalpy of Delta H=1.34 kJ mol(-1) was found, the transition enthalpy derived from the heat capacity is Delta H=1.48 kJ mol(-1)