The rate of sonochemical reduction of Au(III) to produce Au nanoparticles in aqueous solutions containing I-propanol has been found to be strongly dependent upon the ultrasound frequency. The size and distribution of the An nanoparticles produced can also be correlated with the rate of Au(III) reduction, which in turn is influenced by the applied frequency. Our results suggest that the rate of Au(III) reduction as well as the size distribution of An particles are governed by the chemical effects of cavitation and are not significantly affected by the physical effects accompanying ultrasound-induced cavitation.