Abstract: The thermotropic phase transitions in the perovskite type-layer compound (n-C₁₀H₂₁NH₃)₂ZnCl₄ and (n-C₁₂H₂₅NH₃)₂ZnCl₄ were synthesized and a series of their mixtures were prepared from ethanol solutions. Nonisothermal kinetics of solid-solid phase transitions in C₁₀Zn, C₁₈Zn and their binary system was investigated by DSC. Kissinger and Ozawa methods were applied to determine the activation energy and reaction order of the solid-solid transitions. The results of two methods are in agreement.