Decomposition of crystalline and amorphous titanium(IV)oxo-acetylacetonate chemicals have been studied in situ up to 800 °C in flowing air by simultaneous thermogravimetric and differential thermal analysis coupled online with quadrupole mass spectrometer (TG/DTA-MS) and FTIR spectrometric gas cell (TG-FTIR) for the analysis of evolved gases (EGA) in order to get more information about pyrolytic processes taking place at elevated temperatures during smooth TiO 2 layer processing. Crystalline samples (characterized by XRD, PDF 00-35-1778 reference pattern) are releasing acetylacetone (acacH) vapors already from 140 °C onwards. At 245 °C, after an acceleration of this release process, a huge and sharp exothermic heat effect also occurs and results in additional evolution of acetic acid, CO 2, H 2O, and CO. Minute amount of unidentified volatile species with ion fragments not higher than m/ z = 152 are also detected up to 285 °C. The remaining organic residues are burning out from the solid phase in two further exothermic stages until 500 °C. While an amorphous hydrated sample (with low acetylacetonate content) releases first 6.6% of water vapor until 140 °C, then acetone and acetylacetone up to 300 °C. Between 215 and 385 °C, some acetic acid, CO 2, and CO is also evolved. Formation of CO 2 is detected till 650 °C. At 800 °C, the anatase: rutile TiO 2-ratio were 11:89 and 84:16 for the well-crystallized and the amorphous sample, respectively.