The catalytic activity of nanosized Au/gamma-Al2O3, synthesized by a deposition-precipitation process, on oxidative decomposition of hydrazine in air is discussed. The catalyst exhibited an excellent activity at low temperatures. The activity was strongly dependent upon the gold cluster size. The impacts of certain pertinent operating parameters including the particle size of the catalyst, temperature, hydrazine concentration, and feed flow rate on the extent of the reaction were investigated. The results were reproducible with a mean absolute deviation of 3%. Deactivation of the catalyst during the reaction was found to be unlikely. Finally, a kinetic model based on the Eley-Rideal formulation was proposed for the reaction and a correlation was made between the data predicted from the model and those determined experimentally.