This work is concerned with the kinetics of the chlorination process for making aluminum. The method investigated consisted of a conventional thermogravimetric unit comprised of a cahn electrobalance and a vertical tube furnace. Small samples of al2o3:3c mixtures were reacted with he-cl2 atmospheres under isothermal conditions. The reduction kinetics were deduced from the weight loss measurements. Temperature has a particularly strong effect on the reduction kinetics, suggesting that the chemical kinetic factors are very dominant in this system. The rate constant shows a first-order dependence on chlorine pressure at low temperatures (about 750 deg c), but the dependence becomes highly nonlinear at 900 deg c and above. The reaction kinetics were strongly improved by catalytic reagents, the foremost among these being the fluorides of sodium and calcium. The latter is inexpensive and potentially the most attractive of the catalytic additives found. The mechanism of catalysis involves complex mixed fluoride-chloride species acting as active intermediates.