A kinetic study on the gas phase hydrolysis of Alcl(3) was carried out in a 0.5 L'batch reactor in the temperature range 150-210 degrees C with varying AlCl3 and H2O concentrations. The concentrations of HCI produced from the hydrolysis were measured with time during the hydrolysis that lasted for 300 s An overall rate equation involving four kinetic parameters was proposed (r)(Alcl3) = - {(Ae(-E/RT)[Alcl3](alpha)[H2O])/(1 + beta[H2O]} A, E, alpha, and beta were determined to be 1.85 x 10(9) L-227/mol(.s)(227) 35.8 kJ/mol, 2.27, and 873.7 L/mol, respectively, by nonlinear regression to best fit measured HCl concentrations. The kinetics of the first elimination of chlorine was compated between experimental data and predictin based on transition state theory. The rate equation proposed in this study may be useful for the design and simulation of a reactor for producing alumina particles by gas-phased hydrolysis of aluminum chloride.