Abstract: The kinetics of U( VI ) reextraction and U( IV ) extraction in the process of U( VI ) electro-reduction with the system of HNO3-N2H5NO3(H2O)/UO2(NO3)2-HNO3(30% TBP-OK) is investigated with a constant interfacial area cell (Lewis cell) with cathode and anode in it. According to the experimental results and data processing, the apparent activation energy of the U( VI ) reextraction process is 36. 02 kJ/mol. The U( VI ) reextraction rate increases when the stirring speed of two phases increases. This process is mainly diffusion controlled. For the U (IV ) extraction process, the apparent activation energy is 21.13 kJ/mol. The U( IV ) extraction rate also increases when the stirring speed of two phases increases. This process is mainly diffusion controlled. The lower the potential of cathode is, the higher are the rates of U( VI) reextraction and U( IV ) extraction.