The formation of the hydrated electron through the secondary reaction, H + OH- -> H2O + e(aq), has been examined in the sonolysis of argon-saturated aqueous solutions at an ultrasound frequency of 355 kHz. The detection of the hydrated electron was achieved by measuring its reaction with the one-electron acceptors Fe(CN)(6)(3-) and methyl viologen. The results obtained indicate that hydrated electrons are produced predominately at the bubble/aqueous solution interface at comparatively high local concentrations, estimated to be >> 1.5 x 10(-3) M. The half life of the hydrated electron under such conditions is estimated to be << 60 ns.