Abstract Heat capacities of KSCN and NH4SCN crystals were measured by adiabatic calorimetry in the temperature range between 13 K and the melting points. Molar volume of NH4SCN was also determined above room temperature. Entropy change for the II-I transition of KSCN (414.54 K, essentially higher order but accompanied with the first order component) is 6.26 J K−1 mol−1 (=1.09 R In 2), which is of similar magnitude with our previous value (Bull. Chem. Soc. Jpn., 36, 1025 (1963)). Entropy change for the III-II transition of NH4SCN (360.1 K,first order) is 10.01 J K−1 mol−1 and apparent entropy change for the II-I transition of NH4SCN (392.8 K, higher order) is 2.85 J K−1 mol−1 (=0.49 R In 2) in spite of possibly similar nature of the transition with the II-I transition of KSCN. A possibility has been suggested that the entropy change might be approximately R In 2 if the transition was not interfered with the III-II trasition and the premelting.