Abstract: The reaction kinetics between Ag2+ and acetic acid in nitric acid medium was studied by spectrophotometry. The effects of concentrations of acetic acid (HAc), H+, NO3－ and temperature on the reaction were investigated, and the rate equation and the corresponding parameters were obtained. The rate equation is determined as follows: －dc(Ag2+)/dt＝ kc(Ag2+)c(HAc)c－1(H+), where the rate constant is (61015) (mol/L)－1•min－1 at 25 ℃, and the activation energy is (48.8±3.5) kJ•mol－1. The reduction rate of Ag2+ can be improved by either increasing the HAc concentration and the temperature, or decreasing the concentration of nitric acid. However, the effect of concentration of NO3－ on the reduction rate of Ag2+ is negligible.