For a specific set of conditions applied in experimental hot-wall reactor investigations for depositing alpha-Al2O3 from precursor gas mixtures containing AlCl3, kinetic modelling of the gas-phase reactions was carried out on the basis of rate parameters collected or estimated by Catoire and Swihart. Calculations are presented for upward flow rates of 200, 20, 0.41, and 0.08 slh, a vertical tube kreactor (27 mm id) with a 450 mm isothermal zone (1050 degrees C) and with varying concentrations of AlCl3, CO2, H-2, and HCl in the feed gas at a total pressure of 0.1 bar. The residence times of the gas in the isothermal zone were 0.1, 1, 48, and 250 s. The results show that AlCl3 decomposes by reacting with CO2 and H-2 to form AlOCl as the major intermediate species. The water-gas shift reaction, CO2 + H-2 = CO + H2O, is found to take place very slowly at short residence times and much faster at higher ones. The H2O generation increases with the AlOCl content in the gas phase. A comparison of the kinetic values with calculated equilibrium compositions shows that for residence times typically used in technical equipment for chemical vapor deposition (CVD), the gas-phase reactions are kinetically controlled at the temperature and pressure selected. The results may be helpful in understanding the complex reaction mechanisms involved in high-temperature CVD of alumina. (c) 2005 The Electrochemical Society.