The solvent extraction method was applied on the wastewater produced during malonate(malonic acid esters) process to recover cobalt. DEHPA and PC88A were used as organic solvent. From separation funnel experiment(batch experiment), the effects of various parameters (pH, cobalt concentration, reaction rate, and stripping temperature) on solvent extraction were examined and these data were used to derive equilibrium curve. A mixer-settler experiment (continuous experiment) of bench scale was also carried out for the plant construction and a McCabe-Thiele diagram was obtained. The results of these experiments indicate that cobalt is recoverable above 99 % and that its purity as cobalt sulfate is higher than 99.9 wt %.