Abstract: The kineties of extraction of uranium (Ⅳ) from hydrochloric acid solutions with HDEHPin cyclohexane have been investigated using the single drop technique. The effects of the concentrations of U(Ⅳ),H⁺ and HDEHP on the extraction rate for U(Ⅳ) have been examined. It is found that the extraction rate is proportional to [U(Ⅳ)] and [(HDEHP)₂]₍₀₎^1/2 but there is no effect with hydrogen-icn concentration in the aqueous solution.The extraction rate was found to increase with the increasing temperature and the apparent activation energy is 41.7 kJ·mol^-1 between 10~40℃.It is suggested that the rate-controlling step may be the chemical reaction of U⁴⁺ with HDEHP monomer at the liquid-liquid interface.