The low-temperature heat capacities of K2ZnCl4 were measured between 5 and 350 K. A phase transition with a heat effect of 30 J mol-1 was found at 144 K. Between the transition temperature and 210 K, the sample shows a slow transformation which is probably related to the distortions of the ZnCl4 tetrahedra. This is in accordance with Raman and DSC experiments. The thermodynamic properties of a compound are given at rounded temperatures.