A new kinetic method for determination of trace uranium (Ⅵ)has been developed, based on the catalytic effect of uranium ( Ⅵ ) on the discoloring reaction of Rhodamine B oxidated by Hydrogen peroxide in nitric acid medium. The influencing factors of the system and the optimum conditions for determination of uranium were investigated in details,and the results showed that the maximum wavelength of absorbance was located at 556 nm, the apparent activation energy Ea was 21.76 kJ/mol, the apparent rate was 6.07 × 10^-4S^-1. The linear range w...