In this work a selective transport of Co(II) and Li(I) ions from acidic chloride solutions through polymer inclusion membranes (PIMs) with Cyanex 301 has been studied. The effect of composition of the polymer membrane has been investigated. The obtained results show that around 98% of Co(II) was transported from the source phase containing 0.01 M Co(II) and 0.01 M Li(I) at pH 4.0 through PIM after 12 h into 3.0 M HCl. The membrane containing 18 wt.% cellulose triacetate (CTA), 32 wt.% Cyanex301 and 50 wt.% o-nitrophenyl octyl ether (ONPOE) showed very good stability, suggesting that there is a possibility of application of the membrane for Co(II) recovery from acidic leach liquor solutions of spent lithium ion batteries (LIBs).