Ag+ ions are reduced in aqueous solutions by a short pulse of high-energy radiation. At the low radiation dose applied, second-order reactions of the early intermediates are negligible. Three elementary processes occur during microseconds after the pulse, in each of which Ag+ is a reactant : e(aq)(-) + Ag+ --> Ag-0 (k = 4.8 x 10(10) M(-1) s(-1)); Ag-0 + Ag+ --> Ag-2(+) (k = 8.5 x 10(9) M(-1) s(-1)); Ag-2(+) + Ag+ --> Ag-3(2+) (k = 2.0 X 10(9) M(-1) s(-1)). The reactions overlap temporally. Computer simulation is used to obtain the rate constants and the absorption spectra of the three species involved. Ag-3(2+) has not yet been detected in water at ambient temperature; it was known to exist only in zeolite cages and frozen organic glasses.