The kinetcs of extraction of cobalt with HEHEHP-kerosene solution from aqueous nitrate solution has been studied using the Lewis Cell.The effects of stirring rate and interfacial area were investigated.In the kinetic region

the influences of concentration of cobalt

hydrogen ion and HEHEHP were mainly studied.The effects of the sulphate

chloride

nitrate and acetate ions in aqueous phase on extraction rate were also discussed. The experimental results indicate that the extraction process may be governed by the mixed mechanism of diffusion and chemical reaction.In the kinetion

region，the extraction Process might be controlled by the following interfacial reactions The apparent rate constant was calculated to be about 3.63×10~(-13)mol·cm~(-2)·s~(-1).The sulphate

nitrate and chloride ions decrease the extraction rate in the order of SO_4~(2-)＞NO~(-3)＞CI~-.On the other hand

the acetate ion could greatly increase the extraction rate.The extraction rate with 0.025mol·L~(-1) acetate ion in aqueous phase is about four times of that without acetate ion.