Research on the extraction of cobalt(II) from sulfate solution by means of liquid surfactant membrane containing D₂EHPA as extractant and SPAN 80 as emulsifier is presented. In this study, it was observed that the extraction rate of cobalt(II) was greatly enhanced by the presence of a sodium acetate and by the increase of pH in the aqueous feed solution. The optimum concentration of D₂EHPA and SPAN 80 in membrane phase were about 5 vol%, 2.5-3.0 vol% respectively. It is also found that the extraction of cobalt ion is promoted as both the Ve/Vw ratio increases and the W/O ratio decreases. But the extraction efficiency of cobalt(II) was reduced with increasing sulfate ions in aqueous feed solution.