The extraction rate of Co^2^+ with di(2-ethylhexyl) phosphoric acid (HDEHP) was determined by the means of single drop method. The effects of the surfactants, trioctyl phosphine oxide (TOPO), sodium dodecyl sulfonate (SDS) and hexadecyl trimethyl ammonium bromide (CTMAB), on the extraction rate of Co^2^+ were investigated. The acceleration in the kinetics in contributed to the associated molecule (HDEHP)~2 TOPO taking part in the extraction process directly. The decrement effects of SDS or CTMAB on the rate of extraction kinetics of Co^2^+ with HDEHP were also observed, which caused by the adsorption of molecules of SDS or CTMAB on the interface and decreased the interfacial adsorption amount of HDEHP. In addition, the extraction rate was reduced by a bigger margin in HDEHP-SDS system. This can be explained in terms of the formation of an electric field at the interface.

Key words: DYNAMICS, COBALT, SURFACTANTS, EXTRACTION