In this work, separation of cobalt(II) over lithium(I) ions from aqueous chloride solutions by synergistic solvent extraction (SX) has been studied. A synergistic mixture of commercial extractants such as bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) and tributyl phosphate (TBP) in kerosene was used as a selective extractant. The investigations were first performed to select optimal conditions for the effective separation including pH of the aqueous phase as well as concentration of synergistic mixture. High selective solvent extraction of cobalt(II) over lithium(I) from chloride solution has been achieved by the mixture of 0.1 M Cyanex 272 and 0.05 M TBP in kerosene while efficient Co(II) stripping has been performed by 0.5 M sulphuric acid.