The TA method and XPA were employed to study thermal decomposition of fluorozirconates M2ZrF6, M5Zr4F21.3H2O, MZrF5.H2O (M - Rb, Cs), Rb2Zr3OF12, Cs2Zr3F14.1.5H2O, ZnZr2F10.7H2O. After cooling the roentgenoluminescence (RL) of products obtained by cutting on completion of endoeffects on DTA curves was determined. Heating of the anhydrous compounds to 450 oC did not lead to decomposition, although a slight decrease of intensity RL was observed. For hydrated fluorozirconates with zirconium-coordinated water and fluorine incorporated in the system of hydrogen bonds, these bonds must be broken in order to produce a compound comparable in intensity with anhydrous fluorides. Thermal decomposition of hydrated fluorozirconates results in the formation of phases (M2ZrF6, Rb2Zr3OF12) representing luminescent compounds.