This bachelor thesis is devoted to characterization and thermal decomposition of Prussian Blue, Fe4[Fe(CN)6]3. In the introduction part, there is literature overview concerning the thermal decomposition and characterization of the Prussian Blue precursor. The result section is divided to three parts, each one describes a different approach to the study of the mechanism of thermally induced decomposition of Prussian Blue in inert atmosphere. The first approach concerns the decomposition in nitrogen atmosphere at 640°C, 800°C and 1000°C. The second case deals with experiments in argon atmosphere at 400°C, 670°C and 1000°C. Finally, the third approach utilizes ?in-situ? high temperature X-ray powder diffraction in nitrogen atmosphere at the temperature range from 60°C to 900°C. 57Fe Mössbauer spectroscopy, X-ray powder diffraction and scanning electron microscopy were used to understand the decomposition mechanism from room temperature to 1000°C.